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São Miguel do Iguaçu, Brazil

Martinez M.A.,Servicio de Investigacion BEM | Ubeda A.,Servicio de Investigacion BEM | Cid M.A.,UEM | Trillo M.A.,Servicio de Investigacion BEM
Cellular Physiology and Biochemistry | Year: 2012

A number of studies have reported that extremely low frequency magnetic fields (ELF-MF) can modulate proliferative processes in vitro; however, the transduction mechanisms implicated in such phenomena remain to be identified. The present study was aimed to determine whether a 50 Hz, 100 μT MF can induce cell proliferation in the human neuroblastoma line NB69, and whether the signaling pathway MAPK-ERK1/2 (Mitogen-Activated Protein Kinase - Extracellular-Signal-Regulated Kinase 1 and 2) is involved in that proliferative response. The cultures were exposed intermittently or continuously to the MF for a 63-hour duration. The continuous treatment did not induce significant changes in cell proliferation. In contrast, intermittent exposure caused statistically significant increase in the percent of cells in phase S of the cell cycle, followed by a significant increase in cell number. The intermittent treatment also induced an early, transient and repetitive activation of ERK1/2 that could be involved in the proliferative effects. In fact, both the proliferative response and the repeated activation of ERK1/2 were blocked by PD98059, the specific inhibitor of MEK (ERK kinases 1 and 2). Taken together, the described results indicate that a 50 Hz, 100 μT MF can stimulate proliferation in NB69 cells by triggering MAPK-ERK1/2 signaling at each of the "On" periods of an intermittent exposure. Copyright © 2012 S. Karger AG, Basel. Source

The least limiting water range (LLWR) is considered a modern indicator of soil physical quality for plant growth. The aim of this study was to determine the LLWR for assessing the soil physical quality of a dystroferric Red Latosol (Oxisol) under no-tillage in a crop-livestock integration system. In the crop-livestock integration system of the study area, soybean was planted in the summer and oat (Avena strigosa Schreb) plus ryegrass (Lolium multiflorum Lam) in the winter with different pasture heights during grazing: 7, 14, 21, and 28 cm, and an ungrazed control. Undisturbed soils samples were taken from the layers 0-7.5 and 7.5-15 cm, in which the soil bulk density (Bd), soil water retention and soil resistance to penetration curves were determined, to then calculate the LLWR. The critical soil bulk density (Bdc) was determined for LLWR=0. Regardless of the treatments, it was found that an increase of the soil bulk density requires an increase of soil water contents to maintain soil penetration resistance below 2.5 MPa and a decrease in soil water to ensure adequate soil aeration, mainly in the 0-7.5 cm layer. In the treatments with grazing heights of 21 and 28 cm, the magnitude of LLWR was greater than in the control, suggesting that crop-livestock integration creates a positive soil physical environment, provided that an appropriate stocking is maintained to prevent overgrazing. In the 7 cm treatment, the soil physical degradation was very high in the 0-7.5 cm layer, and certainly predisposes the crops to stress resistance to soil drying and to reduced aeration under prolonged conditions of high soil moisture. A progressive reduction in the proportion of samples with greater bulk density values than the critical density of the 7 cm treatment toward the control was verified, indicating that the treatment effect of excessive animal trampling resulted in a loss of soil physical quality in the 0-7.5 cm soil layer. The grazing height of oat and ryegrass pasture should be maintained above 21 cm to ensure adequate physical soil quality in the 0-7.5 cm soil layer. Source

Machado L.C.,IFMG | Ferreira W.M.,Federal University of Minas Gerais | Scapinello C.,UEM
Revista Brasileira de Zootecnia | Year: 2012

The objectives of this study were to evaluate the digestibility of the nutrients of simplified and semisimplified diets, with and without inclusion of exogenous enzymes and to determine the nutritional value of the fibrous sources. The tested feedstuffs were: alfalfa hay, hay from the upper third of the cassava foliage and cassava leaf meal, using a completely randomized design with 11 diets and 8 repetitions. The treatments were constituted of 1 reference diet, 2 simplified diets and 8 semi-simplified diets (4 enzymatic inclusion). The enzymes used were carbohydrases (alpha-galactosidase, galactomanose, xylanase and beta glucanase) and phytase. It was observed that the digestibility of the nutrients of the diets was influenced by the type of feed studied. Semi-simplified diets presented coefficients inferior to the reference diet and superior to the simplified diets. Exogenous enzymes promoted improvements in the digestibility of the dry matter (DM), organic matter, crude protein and gross energy. It was also observed that great part of the crude protein of the cassava leaf meal complexed, which depreciated the digestibility of diets with high inclusion of this ingredient. The nutritional value of fibrous sources was 1822.7 kcal digestible energy - DE/kgDM and 122,6 g digestible protein - DP/kg DM, for the hay from the upper third of the cassava foliage; 2232.5 kcalDE/kgDM and 155.4 gDP/kgDM for alfalfa hay and 1888.9 kcalDE/kgDM and 73.6 gDP/kgDM for the cassava leaf meal. With the exception of diets with elevated inclusion of cassava leaf meal, the semi-simplified diets presented satisfactory coefficients of digestibility improved by the enzymatic inclusion. © 2012 Sociedade Brasileira de Zootecnia. Source

Trillo M.A.,IRYCIS | Martinez M.A.,IRYCIS | Cid M.A.,UEM | Leal J.,IRYCIS | Ubeda A.,IRYCIS
International Journal of Oncology | Year: 2012

In vitro exposure to power frequency magnetic fields (MF) has been reported to influence cell proliferation and differentiation. However, the nature of the response of different human cancer cell types to these fields has not been sufficiently characterized. The present work investigates the response of two proliferating human cell lines of neuroblastoma (NB69) and hepatocarcinoma (HepG2) to a 42 h, intermittent treatment with a weak, 100 μT, 50 Hz MF, alone or in combination with 0.5 μM all-trans-retinol (ROL), a retinoid currently applied in oncostatic therapies. In each experimental replicate the cell samples were submitted to one of the following treatment combinations: MF+/ROL+, MF+/ROL-, MF-/ROL+ or MF-/ROL-. The proliferative response was determined by cell counting (Trypan blue exclusion), BrdU incorporation and by spectrophotometric analysis of total protein and DNA content. The results show that when administered separately, the two treatments, MF and ROL, significantly enhanced cell proliferation in both cell lines. In NB69 simultaneous administration of MF and ROL induced an additive effect on cell proliferation, associated to increased DNA content. By contrast, in HepG2 the ROL-induced cell proliferation and increased protein content were partially blocked by simultaneous exposure to MF. Taken together, these data show that both agents, a weak MF and ROL at a low concentration, induce proliferative responses in the two assayed human cell lines. However, significant differences were observed between the responses of the two cellular species to the combined treatment with ROL and MF, indicating that the mechanisms underlying the cellular response to each of the two agents can mutually interact in a manner that is cell type-specific. Source

News Article
Site: http://www.materialstoday.com/news/

Using a state-of-the-art ultrafast electron microscope, researchers at the University of Minnesota have recorded the first-ever videos showing how heat moves through nanoscale materials at the speed of sound. The research, published in Nature Communications, provides unprecedented insight into how individual atomic and nanoscale features in materials influence the movement of heat. This insight could aid in the design of better, more efficient materials with a wide range of uses, from personal electronics to alternative-energy technologies. Energy in the form of heat impacts all technologies and is a major factor in how electronic devices and public infrastructure are designed and engineered. It is also the largest form of waste energy in critical applications such as power transmission and transportation, where, for example, roughly 70% of the energy in gasoline is wasted as heat in automobile engines. Materials scientists and engineers have spent decades researching how to control thermal energy at the atomic level in order to recycle and reuse it, with the aim of dramatically increasing energy efficiencies and ultimately driving down the use of fossil fuels. Such work would be greatly aided by actually watching heat move through materials, but capturing images of the basic physical processes at the heart of thermal-energy motion has presented enormous challenges. This is because the fundamental length scales for heat transfer are nanometers and the speeds can be many miles per second. Such extreme conditions have made imaging this ubiquitous process extraordinarily challenging. To overcome these challenges and image the movement of heat energy, the researchers used a cutting-edge ultrafast electron microscope (UEM). This microscope is capable of examining the dynamics of materials at the atomic and molecular scale over time spans measured in femtoseconds (one millionth of a billionth of a second). In this work, the researchers used a brief laser pulse to excite electrons and very rapidly heat crystalline semiconducting materials made of tungsten diselenide and germanium. They then used the microscope to capture slow-motion videos, with the speed slowed by over a billion times, of the resulting waves of energy moving through the crystals. "As soon as we saw the waves, we knew it was an extremely exciting observation," said lead researcher David Flannigan, an assistant professor of chemical engineering and materials science at the University of Minnesota. "Actually watching this process happen at the nanoscale is a dream come true." According to Flannigan, the movement of heat through the semiconducting material looks like ripples on a pond after a pebble is dropped in it; the videos show waves of energy moving at about 6nm per picosecond. Mapping the oscillations of energy, called phonons, at the nanoscale is critical to developing a detailed understanding of the fundamentals of thermal-energy motion. "In many applications, scientists and engineers want to understand thermal-energy motion, control it, collect it, and precisely guide it to do useful work or very quickly move it away from sensitive components," Flannigan said. "Because the lengths and times are so small and so fast, it has been very difficult to understand in detail how this occurs in materials that have imperfections, as essentially all materials do. Literally watching this process happen would go a very long way in building our understanding, and now we can do just that." This story is adapted from material from the University of Minnesota, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.

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