Assignment of the bisulfide bridges in bothropstoxin-I, a Myonecrotic Lys49 PLA2 homolog from bothrops jararacussu snake venom

Bothropstoxin-I (BthTX-I), a Lys49 phospholipase A2 homolog with no apparent catalytic activity, was first isolated from Bothrops jararacussu snake venom and completely sequenced in this laboratory. It is a 121-amino-acid single polypeptide chain, highly myonecrotic, despite its inability to catalyze hydrolysis of egg yolk phospholipids, and has 14 half-cystine residues identified at positions 27, 29, 44, 45, 50, 51, 61, 84, 91, 96, 98, 105, 123, and 131 (numbering according to the conventional alignment including gaps, so that the last residue is Cys 131). In order to access its seven disulfide bridges, two strategies were followed: (1) Sequencing of isolated peptides from (tryptic + SV8) and chymotryptic digests by Edman-dansyl degradation; (2) crystallization of the protein and determination of the crystal structure so that at least two additional disulfide bridges could be identified in the final electron density map. Identification of the disulfide-containing peptides from the enzymatic digests was achieved following the disappearance of the original peptides from the HPLC profile after reduction and carboxymethylation of the digest. Following this procedure, four bridges were initially identified from the tryptic and SV8 digests: Cys50-Cysl31, Cys51-Cys98, Cys61-Cys91, and Cys84-Cys96. From the chymotryptic digest other peptides were isolated either containing some of the above bridges, therefore confirming the results from the tryptic digest, or presenting a new bond between Cys27 and Cys 123. The two remaining bridges were identified as Cys29-Cys45 and Cys44-Cysl05 by determination of the crystal structure, showing that BthTX-I disulfide bonds follow the normal pattern of group II PLA2s. © 2001 Plenum Publishing Corporation.

Bibliographical review of the used tyre in concrete

Due to the progressive increase of vehicles, the number of used tires is globally one of the serious environmental problems faced now. Therefore, several researches have being developed for its reuse. The use of tires' rubber in the concrete is a possible form of its a pplication, aiming a the recycling of this material and the improvement of certain properties, as tenacity, impact resistance, thermal and acoustic isolation. This article presents conclusions that several researchers obtained using the rubberized concrete. Thus there were researched several works enclosing the period of 1993 to 2003, presenting then the results of some characteristics of this concrete such as: physical properties in fresh and hardened state, mechanical properties and properties that remit the durability. The bibliographical revision has as objective to subsidize future researches that can contribute to improve the use of this concrete in civil construction.

Structural analyzes of the use of residues of tires in reinforced concrete

The search for an adequate destination to the tires without use is a problem for many countries. The use of tire rubber in concrete through the partial substitution of the small aggregate has for objective the withdrawal of this material of the environment besides serving as alternative material in places that present sand scarcity. However, to use this type of concrete in civil construction it's necessary to verify its structural behavior. The behavior of the adherence enters the bar of armor and the concrete surrounding it has decisive importance with relation to the load capacity of the structures of reinforced concrete. In this context, this work presents, argues and evaluates the results of the experimental studies for determination of the adherence tension according to pulling up assays pull-out normalized for CEB RC6 and also related in the ASTM C-234 in concrete with and without rubber residues. Armors of nominal diameter of 10,0; 12,5 and 16 mm had been used and concrete contend 10% of rubber fibres in substitution to the sand in volume.

Steel bars identification in reinforced concrete structures by using ANN and magnetic fields

This work proposes a methodology for non destructive testing (NDT) of reinforced concrete structures, using superficial magnetic fields and artificial neural networks, in order to identify the size and position of steel bars, embedded into the concrete. For the purposes of this paper, magnetic induction curves were obtained by using a finite element program. Perceptron Multilayered (PML) ANNs, with Levemberg-Marquardt training algorithm were used. The results presented very good agreement with the expect ones, encouraging the development of real systems based upon the proposed methodology.

Reliability of timber bridges using nailed plywood box beams

The Nailed Box Beam structural efficiency is directly dependent of the flange-web joint behavior, which determines the partial composition of the section, as the displacement between elements reduces the effective rigidity of the section and changes the stress distribution and the total displacement of the section. This work discusses the use of Nailed Plywood Box Beams in small span timber bridges, focusing on the reliability of the beam element. It is presented the results of tests carried out in 21 full scale Nailed Plywood Box Beams. The analysis of maximum load tests results shows that it presents a normal distribution, permitting the characteristic values calculation as the normal distribution theory specifies. The reliability of those elements was analyzed focusing on a timber bridge design, to estimate the failure probability in function of the load level.

Brazilian results on structural masonry concrete blocks

The purpose of this paper is to study the mechanical behavior of concrete blocks and prisms when performing axial compression tests within the Brazilian base of knowledge, intending to foment data of this kind for a world-based network. The blocks were built using five different mixtures in which the quantity of cement and the compacting ratio (density) were varied (during the fabrication process). The three-course-high prisms were assembled using 1 cm (0.39 in.) thick full-bedded joints, always trying to leave the mortar's characteristics constant. The axial compression tests were conducted according to Brazilian practice code recommendations, because most of these standards are very similar to international practice codes. The compressive strength, strains, and rupture form of each mixture studied were recorded. Attempts were made to correlate the strength, efficiency ratio (block strength/prism strength) of the prisms, strains, and rupture form; with the quantity of cement and compacting ratio. The data are presented in tables and figures, and the obtained results are discussed throughout the text. Copyright © 2007, American Concrete Institute. All rights reserved.

Estimate of concrete block texture using image analysis

The texture of concrete blocks is very important and is often the decisive factor when choosing a product, particularly if the building specifications call for high-strength blocks allied to low-cost finish, in which case exposed blocks with a closer texture are often preferred. Furthermore, a closer texture, especially for exteriors, may be a vital factor in ensuring the building's durability. At present, however, there is no standard to quantify the texture of a structural block. Further, when studying masonry blocks compressive strength should never be overlooked. This article discusses a procedure to produce concrete block textures with and without the addition of lime, but still to achieve the required compressive strength. The method used in this study, to evaluate texture, proved to be simpler and cheaper than methods reported by other authors in the literature. The addition of small quantities of lime proved beneficial for both texture and compressive strength. Increasing the amount of lime further, however, only improved texture.

Application of UTHSCSA-Image ToolTM to estimate concrete texture

The texture of concrete blocks is very important and is often the decisive factor when choosing a product, particularly if the building specifications does not dispense with the high resistance of the blocks, but has the purpose of reducing costs with finishing, therefore preferring exposed blocks with a closer texture. Furthermore, a closer texture, especially for exteriors,may be the vital factor of the building's pathology.However, there is so far no standard to quantify the texture of a structural block. This article proposes to apply the freely available UTHSCSA-Image ToolTM program developed by the University of Texas Health Science Center at San Antonio to evaluate the texture of masonry blocks. One aspect that should never be overlooked when studying masonry blocks is compressive strength. Therefore, this work also gets the compressive strength of the blocks with and without the addition of lime. The addition of small quantities of lime proved beneficial for both texture and compressive strength. However, increasing the amount of lime proved to be feasible only to improve texture. © 2012 Taylor & Francis Group.

Identification of steel bars immersed in reinforced concrete based on experimental results of eddy current testing and artificial neural network analysis

This paper presents an experimental research on the use of eddy current testing (ECT) and artificial neural networks (ANNs) in order to identify the gauge and position of steel bars immersed in concrete structures. The paper presents details of the ECT probe and concrete specimens constructed for the tests, and a study about the influence of the concrete on the values of measured voltages. After this, new measurements were done with a greater number of specimens, simulating a field condition and the results were used to generate training and validation vectors for multilayer perceptron ANNs. The results show a high percentage of correct identification with respect to both, the gauge of the bar and of the thickness of the concrete cover. © 2013 Copyright Taylor and Francis Group, LLC.

A semigroups theory approach to a model of suspension bridges

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

Ponte mista de madeira-concreto em vigas treliçadas de madeira

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise teórico-experimental de um tabuleiro misto madeira-concreto composto por vigas circulares

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Caracterização do jardim japonês de Ribeirão Preto - SP e germinação de sementes de pinheiros característicos do estilo

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Impact strength and abrasion resistance of high strength concrete with rice husk ash and rubber tires

The paper discusses the application of High Strength Concrete (HSC) technology for concrete production with the incorporation of Rice Husk Ash (RHA) residues by replacing a bulk of the material caking and rubber tires with partial aggregate volume, assessing their influence on the mechanical properties and durability. For concrete with RHA and rubber, it was possible to reduce the brittleness by increasing the energy absorbing capacity. With respect to abrasion, the RHA and rubber concretes showed lower mass loss than the concrete without residues, indicating that this material is attractive to be used in paving. It is thus hoped that these residues may represent a technological and ecological alternative for the production of concrete in construction works.

Three-dimensional analysis of reinforced concrete members via embedded discontinuity finite elements

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