Influence of the grinding wheel's dive speed on the damage of rectified hardened steels

The world tendency is the increase of the productivity and the production of pieces more and more sophisticated, with high degree of geometric and dimensional tolerances, with good surface finish and low cost. Rectification is responsible for the final finish in the machining process of a material. However, damages generated in this production phase affect all the resources used in the previous processes. Great part of the problems happennig in the rectification process is due to the enormous temperature generated in this activity because of the machining conditions. The dive speed, which is directly related to the productivity, is considered responsible for the damages that occur during rectification, limiting its values to those that do not cause such damages. In this work, through the variation of the dive speed in the process of cylindrical grinding of type ABNT D6 steel, rationalizing the application of two cutting fluids and using a CBN (cubic boron nitrate) abrasive wheel with vitrified blond, the influence of the dive speed on the surface damages of hardened steels was evaluated. The results allowed to say that the dive speed, associated to an efficient cooling and lubrication, didn't provoke thermal damages (including heated zones, cracks and tension stresses) to the material. Residual stresses and the roughness of rectified materials presented a correlation with the machining conditions. The work concluded that it is possible to increase the productivity without provoking damages in the rectified components.

Effects of Milling on Surface Integrity of Low-Carbon Steel

This work measured the effect of milling parameters on the surface integrity of low-carbon alloy steel. The Variance Analysis showed that only depth of cut did not influence on the workpiece roughness and the Pearson's Coefficient indicated that cutting speed was more influent than tool feed. All cutting parameters introduced tensile residual stress in workpiece surface. The chip formation mechanism depended specially on cutting speed and influenced on the roughness and residual stress of workpiece.

Projeto de Sistemas Integrados de Propósito Geral Baseados em Redes em Chip Expandindo as Funcionalidades dos Roteadores para Execução de Operações: A plataforma IPNoSys

It bet on the next generation of computers as architecture with multiple processors and/or multicore processors. In this sense there are challenges related to features interconnection, operating frequency, the area on chip, power dissipation, performance and programmability. The mechanism of interconnection and communication it was considered ideal for this type of architecture are the networks-on-chip, due its scalability, reusability and intrinsic parallelism. The networks-on-chip communication is accomplished by transmitting packets that carry data and instructions that represent requests and responses between the processing elements interconnected by the network. The transmission of packets is accomplished as in a pipeline between the routers in the network, from source to destination of the communication, even allowing simultaneous communications between pairs of different sources and destinations. From this fact, it is proposed to transform the entire infrastructure communication of network-on-chip, using the routing mechanisms, arbitration and storage, in a parallel processing system for high performance. In this proposal, the packages are formed by instructions and data that represent the applications, which are executed on routers as well as they are transmitted, using the pipeline and parallel communication transmissions. In contrast, traditional processors are not used, but only single cores that control the access to memory. An implementation of this idea is called IPNoSys (Integrated Processing NoC System), which has an own programming model and a routing algorithm that guarantees the execution of all instructions in the packets, preventing situations of deadlock, livelock and starvation. This architecture provides mechanisms for input and output, interruption and operating system support. As proof of concept was developed a programming environment and a simulator for this architecture in SystemC, which allows configuration of various parameters and to obtain several results to evaluate it

Estudo da viabilidade do desenvolvimento de sistemas integrados baseados em redes em chip sem processadores: sistema IPNoSys

The increase of capacity to integrate transistors permitted to develop completed systems, with several components, in single chip, they are called SoC (System-on-Chip). However, the interconnection subsystem cans influence the scalability of SoCs, like buses, or can be an ad hoc solution, like bus hierarchy. Thus, the ideal interconnection subsystem to SoCs is the Network-on-Chip (NoC). The NoCs permit to use simultaneous point-to-point channels between components and they can be reused in other projects. However, the NoCs can raise the complexity of project, the area in chip and the dissipated power. Thus, it is necessary or to modify the way how to use them or to change the development paradigm. Thus, a system based on NoC is proposed, where the applications are described through packages and performed in each router between source and destination, without traditional processors. To perform applications, independent of number of instructions and of the NoC dimensions, it was developed the spiral complement algorithm, which finds other destination until all instructions has been performed. Therefore, the objective is to study the viability of development that system, denominated IPNoSys system. In this study, it was developed a tool in SystemC, using accurate cycle, to simulate the system that performs applications, which was implemented in a package description language, also developed to this study. Through the simulation tool, several result were obtained that could be used to evaluate the system performance. The methodology used to describe the application corresponds to transform the high level application in data-flow graph that become one or more packages. This methodology was used in three applications: a counter, DCT-2D and float add. The counter was used to evaluate a deadlock solution and to perform parallel application. The DCT was used to compare to STORM platform. Finally, the float add aimed to evaluate the efficiency of the software routine to perform a unimplemented hardware instruction. The results from simulation confirm the viability of development of IPNoSys system. They showed that is possible to perform application described in packages, sequentially or parallelly, without interruptions caused by deadlock, and also showed that the execution time of IPNoSys is more efficient than the STORM platform

Avaliação da execução de aplicações orientadas à dados na arquitetura de redes em chip IPNoSys

The increasing complexity of integrated circuits has boosted the development of communications architectures like Networks-on-Chip (NoCs), as an architecture; alternative for interconnection of Systems-on-Chip (SoC). Networks-on-Chip complain for component reuse, parallelism and scalability, enhancing reusability in projects of dedicated applications. In the literature, lots of proposals have been made, suggesting different configurations for networks-on-chip architectures. Among all networks-on-chip considered, the architecture of IPNoSys is a non conventional one, since it allows the execution of operations, while the communication process is performed. This study aims to evaluate the execution of data-flow based applications on IPNoSys, focusing on their adaptation against the design constraints. Data-flow based applications are characterized by the flowing of continuous stream of data, on which operations are executed. We expect that these type of applications can be improved when running on IPNoSys, because they have a programming model similar to the execution model of this network. By observing the behavior of these applications when running on IPNoSys, were performed changes in the execution model of the network IPNoSys, allowing the implementation of an instruction level parallelism. For these purposes, analysis of the implementations of dataflow applications were performed and compared

Implementação da técnica de software pipelining na rede em chip IPNoSyS

Alongside the advances of technologies, embedded systems are increasingly present in our everyday. Due to increasing demand for functionalities, many tasks are split among processors, requiring more efficient communication architectures, such as networks on chip (NoC). The NoCs are structures that have routers with channel point-to-point interconnect the cores of system on chip (SoC), providing communication. There are several networks on chip in the literature, each with its specific characteristics. Among these, for this work was chosen the Integrated Processing System NoC (IPNoSyS) as a network on chip with different characteristics compared to general NoCs, because their routing components also accumulate processing function, ie, units have functional able to execute instructions. With this new model, packets are processed and routed by the router architecture. This work aims at improving the performance of applications that have repetition, since these applications spend more time in their execution, which occurs through repeated execution of his instructions. Thus, this work proposes to optimize the runtime of these structures by employing a technique of instruction-level parallelism, in order to optimize the resources offered by the architecture. The applications are tested on a dedicated simulator and the results compared with the original version of the architecture, which in turn, implements only packet level parallelism

Saliva substitute in combination with high-concentrated fluoride toothpaste: Effects on demineralised dentin in vitro

Objectives: The aim of this in vitro study was to assess the effects of saliva substitutes (modified with respect to calcium, phosphates, and fluorides) in combination with a high-concentrated fluoride toothpaste on demineralised dentin.Methods: Before and after demineralisation of bovine dentin specimens (subsurface lesions; 37 degrees C, pH 5.0, 5 d), one-quarter of each specimen's surface was covered with nail varnish (control of sound/demineralised tissue). Subsequently, specimens were exposed to original Saliva natura (saturation with respect to octacalciumphosphate [S(OCP)]: 0.03; SN 0), or to three lab-produced Saliva natura modifications (S(OCP): 1, 2, and 3; SN 1-3) for 2 and 5 weeks (37 degrees C). An aqueous solution (S(OCP): 2.5) served as positive control (PC). Two times daily (2 min each), Duraphat toothpaste (5000 ppm F(-); Colgate)/saliva substitute slurry (ratio 1:3) was applied gently. Differences in mineral losses (Delta Delta Z) and lesion depths (Delta LD) between values before and after exposure were microradiographically evaluated.Results: After both treatment periods specimens immersed in SN 0 revealed significantly higher mineral losses (lower Delta Delta Z values) and lesion depths (lower Delta LD) compared to PC (p < 0.05; ANOVA). After 5 weeks, specimens stored in SN 1 and 2 showed significantly higher mineral losses compared to PC (p < 0.05), while those stored in SN 3 showed similar results (p > 0.05). No differences in mineral loss could be observed between SN 2 and 3 (p > 0.05).Conclusions: Under the conditions of this limited protocol, the combination of Saliva natura solutions slightly saturated with respect to OCP in combination with a high-concentrated fluoride toothpaste enabled remineralisation of dentin in vitro. Crown Copyright (c) 2009 Published by Elsevier Ltd. All rights reserved.

Xylanase production by Aspergillus awamori under solid state fermentation conditions on tomato pomace

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

The Influence of Chemical Activation on Tooth Bleaching Using 10% Carbamide Peroxide

The aim of this study was to assess the influence of manganese gluconate, a chemical activator of bleaching agents, at a concentration of 0.01% on the efficiency of a 10% carbamide peroxide-based bleaching agent. Forty bovine incisors were immersed in a 25% instant coffee solution for seven days and randomly divided into two groups. Group 1 was the control group and consisted of 10% carbamide peroxide-based bleaching gel only. Group 2 consisted of 10% carbamide peroxide-based bleaching gel and 0.01% manganese gluconate. Three readings of color were taken using the Vita Easy-shade spectrophotometer: the initial reading, a reading at seven days, and a reading at 14 days. Total color variation was calculated by Delta E*Lab. Data were submitted to the statistical t-test (5%), which showed that after seven days group 2 had a significant increase in the degree of tooth bleaching compared with group 1. The mean values (+/-SD) were 16.33 (+/-3.95) for group 1 and 19.29 (+/-4.97) for group 2. However, the results for group 1 and group 2 were similar after 14 days. Adding 0.01% manganese gluconate to 10% carbamide peroxide bleaching gel increased the degree of tooth bleaching after a seven-day treatment and did not influence the resulting shade after 14 days.

LIMITS on THE COUPLING CONSTANT of HIGHER-DERIVATIVE ELECTROMAGNETISM

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Common vampire bat attacks on humans in a village of the Amazon region of Brazil

Agressões de morcegos a pessoas vêm sendo notificadas em várias comunidades amazônicas nesta última década. Isto constitui um risco potencial para a raiva humana transmitida por morcegos. O objetivo deste estudo foi de analisar fatores associados a estas agressões em uma destas comunidades. Foi realizado um estudo transversal em um povoado de garimpeiros na Região Amazônica brasileira (160 habitantes). Foi realizada a captura de morcegos junto às casas e foram enviadas amostras para o laboratório. Das 129 pessoas entrevistas, 41% foram agredidas por morcegos pelo menos uma vez, com 92% das mordidas localizadas nos dedos dos pés. Por meio de regressão logística, encontrou-se que adultos eram agredidos ao redor de quatro vezes mais do que crianças (OR = 3,75, IC: 1,46-9,62, p = 0,036). Homens foram agredidos com maior freqüência do que mulheres (OR = 2,08, IC: 0,90-4,76, p = 0,067). Nove Desmodus rotundus e três morcegos frugívoros foram capturados e resultaram negativos para a raiva. O estudo sugere que, em áreas de garimpo, adultos do sexo masculino têm maior probabilidade de serem agredidos por morcegos. As ações de controle para a raiva humana a serem desenvolvidas nestes lugares devem dar ênfase especial a adultos homens. Recomendam-se mais investigações sobre o modo como o garimpo na Região Amazônica está colocando em risco as pessoas e o ambiente.

Effect of rotary or manual instrumentation, with or without a calcium hydroxide/1% chlorhexidine intracanal dressing, on the healing of experimentally induced chronic periapical lesions

Objective. To evaluate the healing of experimentally induced chronic periapical lesions in dogs at 30, 75, and 120 days after root canal instrumentation with rotary NiTi files or manual K-files, with or without a calcium hydroxide/1% chlorhexidine paste intracanal dressing.Study design. The second, third, and fourth mandibular premolars and the second and third maxillary premolars of 5 dogs (12 to 18 months of age, weighing 8 to 15 kg) were selected for treatment (a total of 82 root canals). After pulp removal, the root canals were left exposed to the oral cavity for 7 days to allow microbial contamination, after which the root canals were sealed with ZOE cement until periapical lesions were confirmed with radiography. Group I and II teeth were instrumented with manual K-files using the crown-down technique. In group III and IV teeth, NiTi rotary files were used. The apical delta was perforated by using #20 to #30 K-files at the length of the tooth, thus creating a standardized apical opening. The apical stop was enlarged to size 70, with 2.5% sodium hypochlorite irrigation at each file change. Teeth in groups II and IV were dressed with calcium hydroxide (Ca(OH)(2))/1% chlorhexidine (CHX) paste for 15 days before root filling. Group I and III teeth did not receive an intracanal dressing. The access openings of the teeth were permanently restored with silver amalgam condensed on a glass ionomer cement base. Pairs of standardized periapical radiographs were taken at the beginning of the treatment (0 days) and at 30, 75, and 120 days after filling.Results. There was no significant difference in the rate of radiographic healing of the periapical lesions between manual and rotary instrumentation. Radiographs taken at 120 days showed that the treatment with Ca(OH)(2)/1% CHX paste resulted in a significant reduction in mean size of the periapical lesions in comparison to single-session treatment. These findings were also true for histologic observations.Conclusion. The findings support the hypothesis that, regardless of the instrumentation technique (manual or rotary), the use of an intracanal dressing is important in the endodontic treatment of dog's teeth with experimentally induced chronic periapical lesions.

Effect of different irrigation solutions and calcium hydroxide on bacterial LPS

Aim To evaluate the effect of biomechanical preparation with different irrigating solutions and calcium hydroxide dressing in dog root canals containing bacterial endotoxin (lipopolysaccharides; LPS).Methodology One hundred and forty premolar roots from seven dogs were filled with Escherichia coli LPS for 10 days (three roots were lost during histological processing). The following irrigating solutions were used for biomechanical preparation: 1% (group I, n = 20), 2.5% (group II, n = 19) and 5% sodium hypochlorite (group III, n = 19), 2% chlorhexidine digluconate (group IV, n = 20) and physiological saline solution (group V, n = 19). In group VI (n = 20), the LPS solution was maintained in the root canal during the entire experiment and in group VII (n = 20), after biomechanical preparation with saline solution, the root canals were filled with a calcium hydroxide dressing (Calen; control). After 60 days, the animals were sacrificed and the following parameters of periapical disease were evaluated: (a) inflammatory infiltrate, (b) periodontal ligament thickness, (c) cementum resorption and (d) bone resorption. Scores were given and data were analysed statistically with the Kruskal-Wallis and Dunn tests (P < 0.05).Results Histopathological evaluation showed that groups I-VI had more inflammatory infiltrate, greater periodontal ligament thickening and greater cementum and bone resorption (P < 0.05) compared to group VII, which received the calcium hydroxide intracanal dressing.Conclusions Biomechanical preparation with the irrigating solutions did not inactivate the effects of the endotoxin but the calcium hydroxide intracanal dressing did appear to inactivate the effects induced by the endotoxin in vivo.

Influence of root canal dressings and sealers on repair of apical periodontitis after endodontic treatment

Objective. The objective of this study was to evaluate the histopathologic response of periapical tissues after root canal treatment of necrotic dog teeth with chronic apical periodontitis by using 2 calcium hydroxide-based root canal dressings and 2 root canal sealers.Study design. Seventy-eight root canals were instrumented by using 5.25% sodium hypochlorite as the irrigating solution, after which a calcium hydroxide paste (Calen/PMCC or Calasept) was placed for 30 days as a dressing. The root canals were then filled by using cold lateral gutta-percha condensation and an enclodontic sealer (Sealapex or AH Plus). After 360 days, the animals were killed by anesthetic overdose; then, the teeth were histologically prepared, sectioned, and stained with hematoxylin and eosin for optical microscopic analysis of apical and periapical tissue repair.Results. Statistical analysis showed that the poorest histopathologic results were observed in the Calasept/AH Plus group and that the Sealapex sealer overall resulted in better apical repair than the AH Plus sealer. The histopathologic results of Calen/PMCC paste with both AH Plus and Sealapex and Calasept paste with only Sealapex were statistically similar but were different from the results of Calasept with AH Plus.Conclusions. The results of this study in the dog showed differences in apical and periapical tissue repair of teeth with chronic apical periodontitis by using 2 calcium hydroxide root canal dressings and 2 sealers. More research is necessary to determine the best combination of dressings and sealers.