Investigação tecnológica de arenitos silicificados da Formação Botucatu (ne do Paraná) para uso como rocha de revestimento

For many years the silicified sandstone associated of the Botucatu Formation has been the target of interest to researchers and miners, either for understanding the genesis of silicification or for your use as dimension stone and covering on the building industry. If in the first there are several articles available in the geological literature the second there are only technical data marketing available. In the northeast portion of the Paraná State and southwest of the São Paulo State these rocks are mined and traded as covering stones. Not much is known about their intrinsic characteristics and technological properties. To improve the knowledge of the technological behavior of these materials, samples from a quarry from Ribeirao Claro region were petrographically and physically characterized according to the standards established by the Brazilian Association of Technical Standards to dimension stones. Therefore, two bulk samples of silicified sandstone of the Ribeirão Claro/PR region were studied and characterized following the norms established by Brazilian Association of Technical Standards for dimension stones. The results obtained in the petrographical and technological studies are presented and indicated that, in general, the technological performance presented by sandstone studied induces limitations of use as covering materials, mainly horizontally as pavements, door stone and step ladder.

ASPECTOS GEOLÓGICOS, PETROGRÁFICOS E QUÍMICOS DE INTERESSE PARA O APROVEITAMENTO ECONÔMICO DOS QUARTZITOS FOLIADOS DE SÃO THOMÉ DAS LETRAS – MINAS GERAIS

A região de São Thomé das Letras constitui o maior centro brasileiro de lavra de quartzitos foliados, com produção atual estimada em 250.000 t/ano. O baixo índice de recuperação decorrente das atividades de lavra destes quartzitos, estimada como inferiores a 20% do total extraído, estariam gerando cerca de 1.250.000 t/ano de rejeitos, o que tem se traduzido em grandes pilhas de bota-fora com evidentes desdobramentos ambientais indesejáveis. Objetivando a adequação ambiental da lavra, a Fundação Estadual do Meio Ambiente de Minas Gerais - FEAM iniciou, a partir do ano de 1993, trabalhos de fiscalização e orientação da atividade extrativa de quartzitos no Município de São Thomé das Letras. A partir de 1996, esses trabalhos foram ampliados através do Projeto Minas Ambiente - Mineração de Pedra São Tomé que, sob a coordenação da FEAM, promoveu estudos para disposição controlada e aproveitamento econômico de resíduos, revegetação das pilhas de bota-fora e técnicas menos impactantes de desmonte na lavra. Neste contexto, os estudos geológicos, petrográficos e químicos ora realizados visam contribuir com aspectos de interesse para as atividades extrativas e de aproveitamento industrial dos rejeitos da lavra e do beneficiamento dos quartzitos foliados São Tomé. Trabalhos desenvolvidos no âmbito do Projeto Minas Ambiente e, mais recentemente, pela Universidade Vale do Rio Verde de Três Corações demonstraram a viabilidade técnica de utilização dos quartzitos para elaboração de tijolos prensados e autoclavados. Algumas variedades de quartzitos também estão sendo aproveitadas na produção de vidrados e esmaltes cerâmicos, inclusive com vantagens técnicas e econômicas bastante competitivas sobre matérias-primas oriundas de sedimentos aluvionares. Outros usos para os quartzitos moídos, como carga mineral, material filtrante e argamassas em geral, estão em fase de estudos pelos mineradores e deverão ser brevemente viabilizados, o que permite vislumbrar, pelo menos a médio prazo, um expressivo incremento dos usos industriais para os quartzitos São Tomé. Palavras-chave: rocha ornamental; rocha de revestimento; quartzito laminado; recuperação de rejeito; quartzito São Tomé.

Comparative study on extracts from the tissue covering the stingers of freshwater (Potamotrygon falkneri) and marine (Dasyatis guttata) stingrays

Stingrays are elasmobranchs found along the seacoast and in some rivers of Brazil. Pain is the most conspicuous symptom observed in patients wounded by the bilaterally retroserrate stingers located in the tail, which are covered by glandular and integument tissues. In addition, cutaneous necrosis is commonly observed in injuries caused by freshwater stingrays. The aim of this work was to characterize and compare certain properties of tissue extracts obtained from the glandular tissues covering the stinger apparatus of Potamotrygon falkneri and Dasyatis guttata stingrays. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), tissue extracts have similar bands above 80kDa, but most differences were observed below this molecular mass. Lethal, dermonecrotic and myotoxic activities were detected only in P. falkneri tissue extract. Edematogenic activity was similar and dose dependent in both tissue extracts. Nociceptive activity was verified in both tissue extracts, but P. falkneri presented a two-fold higher activity than D. guttata tissue extract. No direct hemolysis, phospholipase A(2) and coagulant activities were observed in both tissue extracts. Antigenic cross-reactivity was noticed by ELISA and Western blotting, using antisera raised in rabbits. Species-specific sera reacted with several components of both tissue extracts, noticeably above 22 kDa. Both tissue extracts presented gelatinolytic, caseinolytic and fibrinogenolytic activities, which were not caused by the action of metalloproteinases. Hyaluronidase activity was detected only in P. falkneri tissue extract. Our experimental observations suggest that P. falkneri tissue extract is more toxic than D. guttata tissue extract. These results may explain why injuries caused by freshwater stingrays are more severe in human accidents. (c) 2007 Elsevier Ltd. All rights reserved.

Uranium distribution and radon exhalation from Brazilian dimension stones

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Seeder-fertilizer machine: energetic demand as a function of vegetal covering handling and manure deposition shank depth in no-tillage system

O trabalho teve por objetivo avaliar a demanda energética de uma semeadora-adubadora, em função do tipo e manejo da cultura de cobertura vegetal e da profundidade da haste de deposição de adubo. Foi utilizado um trator Valtra BM100, instrumentado, para tracionar uma semeadora-adubadora de precisão equipada com quatro fileiras de semeadura espaçadas de 0,9 m para cultura de milho. O experimento foi conduzido em parcelas subsubdivididas, na área experimental do Laboratório de Máquinas e Mecanização Agrícola (LAMMA) da UNESP-Jaboticabal, utilizando duas culturas de cobertura (mucuna-preta e crotalária), três manejos dessas coberturas, sendo dois mecânicos (triturador de palhas e rolo-faca) e um químico (pulverização com herbicida), realizados 120 dias após a semeadura das culturas de cobertura e três profundidades da haste de deposição do adubo (0,11; 0,14 e 0,17 m), perfazendo 18 tratamentos, com quatro repetições, totalizando 72 observações. Foram avaliados os parâmetros velocidade de deslocamento, patinagem, força na barra de tração, força de pico, potência na barra de tração, potência de pico e consumo de combustível. Pôde-se concluir que a força na barra de tração foi menor para as profundidades de 0,11 e 0,14 m da haste sulcadora de adubo, o mesmo ocorrendo para força de pico, potência na barra de tração e consumo volumétrico. O consumo específico foi menor na profundidade de 0,17 m da haste sulcadora de adubo. As culturas de cobertura e seus manejos não interferiram no desempenho das máquinas estudadas.

EVALUATION of COVERING MATERIALS IN INDIVIDUAL SHELTERS and ITS EFFECTS on PHYSIOLOGICAL RESPONSES and PERFORMANCE of DAIRY CALVES

In Tropical regions, the animal performance is often affected by climate conditions. This study aimed to evaluate covering materials in individual shelters, normally used to house dairy calves, and its influence on the calves physiology and performance. The design used was completely randomized, with a 2x3 factorial arrangement to compare the averages of 5% through the Tukey's test, i.e., both genders-and three types of covering in the shelters (Z - zinc; AC - asbestos cement; and WPAC - white-painted asbestos cement). Parameters evaluated included daily weight gain (DWG), dry matter intake (DMI), feed conversion (FC), rectal temperature (RT), and respiratory frequency (RF). Results showed significant differences (P < 0.05) among males (1.04kg/day) and females (0.74kg/day) for DWG and interaction between gender and treatment (P < 0.05) for zinc covering (0.562kg/day for females and 1.120kg/day for males). Significant differences were also observed in FI of animals housed under shelters with the covering of zinc (48.35kgDM/day for females and 96.91 kgDM/day for males). There were no significant differences (P > 0.05) in the FC and the RT, and there were significant differences (P < 0.05) for RF in the Z treatments (56.9 mov.min(-1)), WPAC (62.2 mov.min(-1)) and FC (70.25 mov.min-1). It was concluded that different covering materials did not affect performance and dry matter intake of dairy calves. However, the animals' physiology of thermoregulation was altered by the different covering materials used in individual shelters.

Histopathological changes induced by extracts from the tissue covering the stingers of Potamotrygon falkneri freshwater stingrays

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

Healing process of dog dental pulp after pulpotomy and pulp covering with mineral trioxide aggregate or Portland cement.

Considering several reports about the similarity between the chemical compositions of the mineral trioxide aggregate (MTA) and Portland cement (PC), the subject of this investigation was to analyze the behavior of dog dental pulp after pulpotomy and direct pulp protection with these materials. After pulpotomy, the pulp stumps of 26 roots of dog teeth were protected with MTA or PC. Sixty days after treatment, the animal was sacrificed and the specimens removed and prepared for histomorphological analysis. There was a complete tubular hard tissue bridge in almost all specimens. In conclusion, MTA and PC show similar comparative results when used in direct pulp protection after pulpotomy.

Sharpening of periodontal instruments with different sharpening stones and its influence upon root debridement--scanning electronic microscopy assessment

The objective of this study was to evaluate, through scanning electronic microscopy, the effect of sharpening with different sharpening stones on the cutting angle of periodontal curettes (Gracey 5-6), and the influence on root surfaces after debridement and planing. The experimental model consisted of two different phases. In the first, the cutting angles of fifteen stainless steel Gracey 5-6 curettes were analyzed under a scanning electronic microscope after being sharpened with different types of stones. In the second phase, the root surfaces of 25 newly extracted teeth were evaluated with a scanning electronic microscope after being debrided with curettes sharpened with different stones. Analysis of the results showed that the synthetic stones (aluminum oxide and carborundum) are more abrasive and produce more irregular cutting angles, whereas Arkansas stones are less abrasive and produce smoother and more defined cutting angles. There was no significant statistical differences among the five groups tested with regard to the degree of irregularity of the root surfaces after instrumentation.

Scanning electron microscopic and profilometric study of different sharpening stones

Scaling and root planing contribute to the recovery of periodontal health. All periodontal instruments loose their fine cutting angle after use. To maintain this angle, correct sharpening is required using specifically designed stones. The characteristics of sharpening stones can be compared to the blade of the instruments and also transported to root surface during instrumentation. Root smoothness is related to the quality of the blade. Therefore, the purpose of this study was to evaluate the characteristics of 9 sharpening stones by scanning electron microscopic and profilometric analyses. Ceramic and Neumar stones were very fine and both may be recommended to maintain the sharpness of the instruments. Arkansas, Thompson and CE stones presented greater roughness with very regular and round particles, and are suitable for maintenance of the cutting angle. In addition, these stones may be indicated for the routine sharpening of the instruments that are partly dull. Oxide Aluminum, Carborundum and JON stones were the coarsest with large irregular particles and may be indicated for initial sharpening of totally dull instruments with completion of sharpening with finer stones.

Rochas ornamentais e de revestimento do sudoeste do estado do mato grosso

Geological, petrographical, chemicals and technological studies of rocks of the southwest region of Mato Grosso State, Brazil have the purpose of qualification and application of these rocks as dimension stones. The first objective is to enlarge the offering of new esthetic varieties that show a standardization of technologic patterns, adequate characterization and classification assuring the correct specification of the rocks in relation to the use as dimension stones. Ten rock types are recognized for dimension stones, including granites, diabases, gneisses and amphibolites grouped by its colors in red, grey and black types and showing economic potential of plowing. The results obtained in the technological essays show that the rock parameters are sited inside the standard limits established by technical rules and obey satisfactorily the limit values fixed for granites in internal and external covering uses.

A decomposition heuristic for the maximal covering location problem

This paper proposes a cluster partitioning technique to calculate improved upper bounds to the optimal solution of maximal covering location problems. Given a covering distance, a graph is built considering as vertices the potential facility locations, and with an edge connecting each pair of facilities that attend a same client. Coupling constraints, corresponding to some edges of this graph, are identified and relaxed in the Lagrangean way, resulting in disconnected subgraphs representing smaller subproblems that are computationally easier to solve by exact methods. The proposed technique is compared to the classical approach, using real data and instances from the available literature. © 2010 Edson Luiz França Senne et al.