Internal Architecture and Population Size of Acromyrmex subterraneus molestans (Hymenoptera, Formicidae) Nests: Comparison Between a Rural and an Urban Area

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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 apical sealing of three endodontic sealers

Aim: The apical sealing ability of three different endodontic sealers was evaluated in extracted teeth using dye penetration. Methodology: The root canals of 99 extracted human maxillary central incisors were prepared sequentially 2 mm beyond the apical foramen with a size 55 Nitiflex file. The teeth were divided into three experimental groups and obturated by lateral condensation of cold gutta-percha and one of the following sealers: group 1, zinc oxide and eugenol sealer (Fill Canal); group 2, glass ionomer sealer (Ketac-Endo) and group 3, epoxy resin sealer (AH Plus). The teeth were covered with nail varnish to within 1 mm of the apical foramen and immersed in 2% methylene blue in a reduced pressure environment for 24h. After this period, the teeth were washed and cut longitudinally for apical leakage analysis. The values were obtained from the maximum depth of leakage as well as the average between the maximum and minimum values observed for each group. Results: Statistical evaluation of the results showed no significant difference in the leakage between Fill Canal and Ketac-Endo (P > 0.05). Leakage with AH Plus was significantly less (P < 0.01) than with the other sealers. Conclusions: All three sealers allowed some leakage to occur. Leakage with AH Plus was significantly different than with Fill Canal or Ketac-Endo.

Benzyladenine and Gibberellic acid pulse on postharvest of Calathea louisae cut foliage

Calathea louisae is an herbaceous ornamental plant native of Brazil whose cut foliage has potential to be used as a new product for the local ornamental market, as well as the international market, due to its decorative dark green leaves with greenish white splotches along midrib, and purple undersides. The objective of this study was to evaluate pulse treatments of benzyladenine and gibberellic acid for maintaining quality and extending keepability of foliage. The experiment was conducted in a complete randomized design with three replications (three stems in each vase) and seven treatments: distilled water (control) and pulsing cut petioles in benzyladenine or gibberellic acid for 4 h at 100, 250 and 500 mg L-1. The senescence symptoms were characterized by leaf rolling and a decrease in the angle formed between leaf and petiole as a response to water stress. Gibberellic acid or benzyladenine pulse treatments (250 and 500 mg L-1) significantly extended the longevity of cut foliage compared to the control. Gibberellic acid pulse (250 and 500 mg L-1) maintained leaves' green coloration and brightness for a longer time compared to control and benzyladenine pulse. Pulsing with gibberellic acid or benzyladenine (at all tested concentrations) maintained upright leaves for a longer time, showing a significantly higher angle between leaf and petiole compared to control. Foliage pulsed with gibberellic acid (500 mg L-1) showed a significantly higher leaf relative water content, a significantly smaller loss of accumulated fresh mass percentage compared to control and other gibbberellic acid and benzyladenine treatments.

Study of cutting forces on machinability properties of gray cast iron using new ceramics cutting tools

During gray cast iron cutting, the great rate of mechanical energy from cutting forces is converted into heat. Considerable heat is generated, principally in three areas: the shear zone, rake face and at the clearance side of the cutting edge. Excessive heat will cause undesirable high temperature in the tool which leads to softening of the tool and its accelerated wear and breakage. Nowadays the advanced ceramics are widely used in cutting tools. In this paper a composition special of Si3N4 was sintering, characterized, cut and ground to make SNGN120408 and applyed in machining gray cast iron with hardness equal 205 HB in dry cutting conditions by using digital controlled computer lathe. The tool performance was analysed in function of cutting forces, flank wear, temperature and roughness. Therefore metal removing process is carried out for three different cutting speeds (300 m/min, 600 m/min, and 800 m/min), while a cutting depth of 1 mm and a feed rate of 0.33 mm/rev are kept constant. As a result of the experiments, the lowest main cutting force, which depends on cutting speed, is obtained as 264 N at 600 m/min while the highest main cutting force is recorded as 294 N at 300 m/min.

Pulse treatments to extend the postharvest life of Ctenanthe setosa cut foliage

Marantaceae leaves have a contrasting color pattern and a decorative design which are interesting traits for its use as cut foliage. No postharvest research has been carried out on the potential as cut foliage for species of Ctenanthe, a member of the Marantaceae. Grey-maranta (Ctenathe setosa) is an herbaceous ornamental plant native of Brazil whose cut foliage has potential to be used as new crop product for local and international ornamental markets. The objective of this study was to evaluate pulse treatments to extend the longevity of foliage. The experiment was conducted in a complete randomized design with three replications and eight treatments: distilled water; pulsing cut petioles-ends in citric acid (pH = 2.8/1h); 2% sucrose (4h); 1% sucrose plus 200 mg L-1 citric acid (4h); 0.01% Tween® 20 (4h); 100 mg L -1 benzyladenine plus 0.01% Tween® 20 (4h); 100 mg L-1 gibberellic acid plus 0.01% Tween® 20 (4h); and maintenance of cut petiole in holding solution with commercial sodium hypochlorite (0.5 mL L-1). The senescence symptoms were mainly characterized by leaf rolling and by a decrease in the angle formed between leaf and petiole as a response to water deficit stress. Gibberellic acid or benzyladenine pulse treatments significantly extended longevity (6 days compared to control) and maintained leaves' green coloration and brightness for a longer time compared to control. However, only the benzyladenine plus Tween® 20 pulse maintained leaves in an erect form for a longer time, showing a significantly higher angle between leaf and petiole compared to control. Also, foliage pulsed with benzyladenine plus Tween® 20 showed a significant smallest loss of accumulated fresh mass percentage compared to control by the T test as to parallelism of treatments lines.

Postharvest characteristics and treatments to overcome latex exuded from cut flowers of lotus

Lotus (Nelumbo nucifera Gaertn.) is a perennial herbaceous aquatic ornamental plant with potential to be used as a new cut flower for the Brazilian ornamental market. It shows exotic and attractive flowers and has a strong market appeal, once it is known as a symbol of purity, holiness and immortality. However, flowers have a short-vase life. Lotus flower stem exudes a large quantity of sticky milky sap from the cut surface, which is produced in laticifers, spatially associated with both xylem and phloem. It has been reported that latex coagulates on the cut surface preventing or reducing water absorption and reducing flowers' vaselife, requiring treatments to stop the flow of latex. The objective of this study was to report observations of lotus postharvest characteristics and evaluate treatments to overcome latex flow. The experiment was conducted as a complete randomized design with three replications of four stems in each vase and eight treatments; a control (distilled water), pretreatment of cut stem-ends with hot water (40° C/1 minute), boiling water (3 seconds), isopropyl alcohol 90% (10 minutes) or citric acid (pH = 2.8/1h) and, maintenance of stems in a holding solution of Tween® 20 (0.01%), citric acid (200 mg L-1) or Tween® 20 (0.01%) plus citric acid (200 mg L-1). Treatments had no significant effect on flowers vaselife which was only about three days, although isopropyl alcohol, hot and boiling water completely stopped latex flow. Cut stem-ends pretreated with citric acid (pH = 2.8/1 h) showed a significantly higher relative water content of petals compared to others treatments. The senescence symptom of lotus cut flowers was mainly characterized by abscission of turgid petals and dehiscence of stamens without any visual change of petal color and brightness.

Influence of air abrasion tips and operation modes on enamel-cutting characteristics

Objective: To assess the influence of air abrasion tips and system operation modes on enamel cutting. Methods: Forty bovine teeth were abraded with the air abrasion system Mach 4.1 for 10 and 15 seconds, employing conventional and sonic tips of 0.45-mm inner diameter and a 90° angle, and 27.5-μm aluminum oxide at 5.51 bar air pressure in continuous and pulsed modes. The width and depth of the resulting cuts were measured in SEM. Results: The multivariate analysis of variances revealed that, compared to the sonic tip, the conventional tip produced shallower cuts independent of the operation mode and the application period. Conclusions: The cutting patterns observed in this study suggest that the pulsed mode produced deeper cuts when both the conventional and sonic tips were used, and that the sonic tip cut more dental tissue than the conventional one.

Effects of litter manipulation in a tropical Eucalyptus plantation on leaching of mineral nutrients, dissolved organic nitrogen and dissolved organic carbon

Although many studies have shown that soil solution chemistry can be a reliable indicator of biogeochemical cycling in forest ecosystems, the effects of litter manipulations on the fluxes of dissolved elements in gravitational soil solutions have rarely been investigated. We estimated the fluxes of NH4-N, NO3-N, K, Ca, Mg, Na, Cl, dissolved organic nitrogen (DON) and dissolved organic carbon (DOC) over the first two years after re-planting Eucalyptus trees in the coastal area of Congo. Two treatments were replicated in two blocks after clear-cutting 7-year-old stands: in treatment R, all the litter above the mineral soil was removed before planting, and in a double slash (DS) treatment, the amount of harvest residues was doubled. The soil solutions were sampled down to a depth of 4 m and the water fluxes were estimated using the Hydrus 1D model parameterized from soil moisture measurements in 4 plots. Isotopic and spectroscopic analytical techniques were used to assess the changes in dissolved organic matter (DOM) properties throughout the transfer in the soil. The first year after planting, the fluxes of NH4-N, K, Ca, Mg, Na, Cl and DOC in the topsoil of the DS treatment were 2-5 times higher than in R, which showed that litter was a major source of dissolved nutrients. Nutrient fluxes in gravitational solutions decreased sharply in the second year after planting, irrespective of the soil depth, as a result of intense nutrient uptake by Eucalyptus trees. Losses of dissolved nutrients were noticeably low in these Eucalyptus plantations despite a low cation exchange capacity, a coarse soil texture and large amounts of harvest residues left on-site at the clear cut in the DS treatment. All together, these results clarified the strong effect of litter manipulation observed on eucalypt growth in Congolese sandy soils. DOM fluxes, as well as changes in delta C-13, C:N and aromaticity of DOM throughout the soil profile showed that the organic compounds produced in the litter layer were mainly consumed by microorganisms or retained in the topsoil. Below a depth of 15 cm, most of the DOC and the DON originated from the first 2 cm of the soil and the exchanges between soil solutions and soil organic matter were low. (C) 2014 Elsevier B.V. All rights reserved.

Spatial distribution of runoff depth from a watershed located in a cuesta relief area of São Paulo State, Brazil

This study was undertaken in a 1566 ha drainage basin situated in an area with cuesta relief in the state of São Paulo, Brazil. The objectives were: 1) to map the maximum potential soil water retention capacity, and 2) to simulate the depth of surface runoff in each geographical position of the area based on a typical rainfall event. The database required for the development of this research was generated in the environment of the geographical information system ArcInfo v.10.1. Undeformed soil samples were collected at 69 points. The ordinary kriging method was used in the interpolation of the values of soil density and maximum potential soil water retention capacity. The spherical model allowed for better adjustment of the semivariograms corresponding to the two soil attributes for the depth of 0 to 20 cm, while the Gaussian model enabled a better fit of the spatial behavior of the two variables for the depth of 20 to 40 cm. The simulation of the spatial distribution revealed a gradual increase in the depth of surface runoff for the rainfall event taken as example (25 mm) from the reverse to the peripheral depression of the cuesta (from west to east). There is a positive aspect observed in the gradient, since the sites of highest declivity, especially those at the front of the cuesta, are closer to the western boundary of the watershed where the lowest depths of runoff occur. This behavior, in conjunction with certain values of erodibility and depending on the land use and cover, can help mitigate the soil erosion processes in these areas.