Exchangeable basic cations and nitrogen distribution in soil as affected by crop residues and nitrogen

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Impedance of carrier injection at the metal-organic interface mediated by surface states in electron-only tris(8-hydroxyquinoline) aluminium (Alq(3)) thin layers

Capacitance spectra of thin (< 200 nm) Alq(3) electron-only devices have been measured as a function of bias voltage. Capacitance spectra exhibit a flat response at high frequencies (> 10(3) Hz) and no feature related to the carrier transit time is observed. Toward low frequencies the spectra reach a maximum and develop a negative excess capacitance. Capacitance response along with current-voltage (J-V) characteristics are interpreted in terms of the injection of electrons mediated by surface states at the metal organic interface. A detailed model for the impedance of the injection process is provided that highlights the role of the filling/releasing kinetics of energetically distributed interface states. This approach connects the whole capacitance spectra to the occupancy of interface states, with no additional information about bulk trap levels. Simulations based on the model allow to derive the density of interface states effectively intervening in the carrier injection (similar to 1.5 x 10(12) cm (2)). (C) 2008 Elsevier B.V. All rights reserved.

Synthesis and thermal studies of solid state 2-chloro-benzylidenepyruvic acid and its compounds with sodium, aluminium (III), gallium (III) and indium (III) cations

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influence of anodization on the fatigue strength of 7050-T7451 aluminium alloy

In recent years, with higher demand for improved quality and corrosion resistance, recovered substrates have been extensively used. Consequently residual stresses originated from these coatings reduce the fatigue strength of a component. Due to this negative influence occasioned by corrosion resistance protective coatings, an effective process like shot peening must be considered to improve the fatigue strength. The shot peening treatment pushes the crack sources beneath the surface in most of medium and high cycle cases due to the compressive residual stress field (CRSF) induced. The aim of this study was to evaluate the influence on the fatigue life of anodic films grown on 7050-T7451 aluminium alloy by sulphuric acid anodizing, chromic acid anodizing and hard anodizing. The influence on the rotating and reverse bending fatigue strength of anodic films grown on the aluminium alloy is to degrade the stress life fatigue performance of the base material.A consistent gain in fatigue life in relation to the base material was obtained through the shot peening process in coated specimens, associated to a residual stress field compressive near the surface, useful to avoid fatigue crack nucleation and delay or even stop crack propagation.

Qualitative and quantitative characterization of aluminium alloys after corrosion testing

The 2024 and 7050 aluminium alloys used as aircraft components were subjected to laboratory corrosion tests in sodium chloride solution, Light-microscope examinations make it possible to characterise morphological aspects of the localised corrosion. Image analysis was used to determine both depth and width of pits over corroded surfaces. It has been concluded that the annealing could reduce the pit growth in both alloys, by means of grains recrystallization or recovery. The 2024 alloy also tends to present an exfoliation mechanism, mainly throughout non-recrystallized and recrystallized grain boundaries, increasing the width and sustaining the depth of pit cavities during exposition to saline atmosphere. SEM and EDS analysis reveal the morphology and elemental distribution of the corrosion products formed after immersion corrosion test. Some of these products were identified by X-ray diffraction analysis. For 2024, Al(OH)(3), MS(OH)(2) and Cu2O were found. AI(OH)(3) and Cu2O were also found in 7050 samples.

A metallurgical study of aluminium alloys used as aircraft components

The effects of heat treatment on morphologies and microstructures of Al 2024 and Al 7050 alloys, used as aircraft components, were studied by metallographic techniques. Light microscopy (LM) and quantitative image analysis were used to characterize the precipitate dispersion and morphology for these alloys. The application of the scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) combined techniques for studying these multiphase systems makes it possible to distinguish and quantify the different phases in the surface structure. Xray diffraction also permitted a qualitative comparison of the structures before and after heat treatments.

Histopathological evaluation of treatment with chondroitin sulphate for osteoarthritis induced by continuous immobilization in rabbits

The aim of this study was to evaluate histologically the action of chondroitin sulphate in osteoarthritis experimentally induced by continuous immobilization. Fourteen young female Norfolk rabbits aged 2.5-3 months at the beginning of the experiment were divided into two equitable groups submitted to immobilization of the right knee for a period of 12 weeks. The treated group received 1.0 ml/animal/s.c. of 12% chondroitin sulphate, once a week for 12 weeks, and the untreated group did not receive any treatment. Two additional animals were not submitted to knee immobilization (sham group). Microscopical examination of knee preparations stained with haematoxylin-eosin and Masson trichrome showed lesions of both joints in treated and untreated groups, with no significant difference between the scores obtained for the right and left knees. Examination of preparations stained with picrosirius red showed collagen fibre alignment and misalignment in the right and left knees of the animals of all groups, but statistic analysis could not be performed. It was not possible to differentiate the proteoglycan concentration between limbs or groups (treated and untreated) by safrtanin O or toluidine blue staining. It was possible to conclude that the chondroitin sulphate was not able to reduce the histological changes induced by this osteoarthritis experimental model.

Computer-Guided Surgery in Implantology: Review of Basic Concepts

The aim of the present study was to conduct a critical literature review about the technique of computer-guided surgery in implantology to highlight the indications, purposes, immediate loading of implants and complications, protocol of fabrication, and functioning of virtual planning software. This literature review was based on OLDMEDLINE and MEDLINE databases from 2002 to 2010 using the key words "computer-guided surgery" and "implant-supported prosthesis." Thirty-four studies regarding this topic were found. According to the literature review, it was concluded that the computer-assisted surgery is an excellent treatment alternative for patients with appropriate bone quantity for implant insertion in complete and partially edentulous arches. The Procera Nobel Guide software (Nobel Biocare) was the most common software used by the authors. In addition, the flapless surgery is advantageous for positioning of implants but with accurate indication. Although the computer-guided surgery may be helpful for virtual planning of cases with severe bone resorption, the conventional surgical technique is more appropriate. The surgical guide is important for insertion of the implants regardless of the surgical technique, and the success of immediate loading after computer-guided surgery depends on the accuracy of clinical and/or laboratorial steps.

Regeneration of class III furcation defects with basic fibroblast growth factor (b-FGF) associated with GTR. A descriptive and histometric study in dogs

Background: the poor predictability of periodontal regenerative treatment of Class III furcation defects stimulates the study of alternatives to improve its results, such as the use of polypeptide growth factors. The objective of this study was to evaluate, both histologically and histometrically, the effects of topical application of basic fibroblast growth factor (b-FGF) associated with guided tissue regeneration (GTR) in the treatment of Class III defects surgically induced in dogs.Methods: All second and fourth premolars of 5 mongrel dogs were used and randomly assigned to one of three treatment groups: group 1 (control), treated with scaling and root planing, tetracycline hydrochloride (125 mg/ml) conditioning, and GTR with a collagen membrane; group 2, same treatment as group 1 plus 0.5 mg of b-FGF; group 3, same treatment as group 1 plus 1.0 mg of b-FGF. After a 90-day healing period, routine histologic processing and staining with hematoxylin and eosin and Masson trichrome were performed.Results: the descriptive analysis indicated better regenerative results in both groups treated with b-FGF while the histometric data, analyzed by means of analysis of variance (ANOVA), showed greater filling of the defects in group 2 in comparison to the defects in groups 3 and 1, respectively, which was represented by a smaller area of plaque-occupied space (P = 0.004) as well as a greater amount of newly formed cementum (P = 0.002).Conclusions: These results indicate that b-FGF, especially in smaller doses, may enhance the regenerative results in Class III furcation lesions, leading to greater filling of these defects with both mineralized and non-mineralized tissues.

Peroxidase activity and total phenol content in citrus cuttings treated with different copper sources

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Cytogenetics studies in Brazilian species of Pseudophyllinae (Orthoptera: Tettigoniidae): 2n(♂)=35 and fn=35 the probable basic and ancestral karyotype of the family tettigoniidae

The karyotypes of five species of Brazilian Pseudophyllinae belonging to four tribes were here studied. The data available in the literature altogether with those obtained with species in here studied allowed us to infer that 2n(♂)=35 is the highest chromosome number found in the family Tettigoniidae and that it is present in species belonging to Pseudophyllinae, Zaprochilinae and in one species of Tettigoniinae. In spite of that all five species exhibit secondary karyotypes arisen surely by a mechanism of chromosomal rearrangement of centric fusion, tandem fusion and centric inversion types from those with 2n(♂)=35 and FN=35, they share some common traits. The X chromosome is submetacentric (FN=36), heteropicnotic during the first prophase, the largest of the set but its size is rather variable among the species and the sex chromosomal mechanism is of the XO( ♂ ), XX( ♀ ) type. The chromosomal rearrangements involved in the karyotype evolution of the Pseudophyllinae and its relationship with those of the family Tettigoniidae are discussed and we propose that the basic and the ancestral karyotype of the Tettigoniidae is formed by 2n(♂)=35, FN=35 and not by 2n(♂)=31, FN= 31, as usually accepted.

Diabetes induces stromal remodelling and increase in chondroitin sulphate proteoglycans of the rat ventral prostate

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

BASIC HYPERGEOMETRIC FUNCTIONS and ORTHOGONAL LAURENT POLYNOMIALS

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)