Discoloration and fungal growth on three fiber cement formulations exposed in urban, rural and coastal zones

Three formulations of fiber cement were evaluated for fungal colonization and color change after five years of exposure in aging stations located in urban (Sao Paulo), rural (Pirassununga) and coastal (Rio Grande) zones in Brazil. The lowest color change and fungal colonization were registered in Rio Grande, which has a temperate climate, as opposed to Sao Paulo and Pirassununga, which are tropical. The highest fungal colonization was recorded in Sao Paulo, one of the most air polluted cities in Brazil. Pirassununga samples had an intermediate fungal colonization, in spite of showing the highest color change with visible dark spots on the surfaces. These spots were identified as cyanobacteria, which significantly contributed to the darkening of the specimens. The fiber cement formulation, varying in proportion of organic fibers such as poly (vinyl alcohol) and cellulose, was less significant for fungal bioreceptivity than the characteristics of the exposure site. The most frequent fungal genus found in the tropical climate, in both urban and rural zones, and the main one responsible for the higher records in Sao Paulo, was Scytalidiurn sp. which was registered for the first time on this building material in Brazil. (C) 2010 Elsevier Ltd. All rights reserved.

Harmonic Distortion State Estimation Using an Evolutionary Strategy

This paper presents a new methodology to estimate harmonic distortions in a power system, based on measurements of a limited number of given sites. The algorithm utilizes evolutionary strategies (ES), a development branch of evolutionary algorithms. The main advantage in using such a technique relies upon its modeling facilities as well as its potential to solve fairly complex problems. The problem-solving algorithm herein proposed makes use of data from various power-quality (PQ) meters, which can either be synchronized by high technology global positioning system devices or by using information from a fundamental frequency load flow. This second approach makes the overall PQ monitoring system much less costly. The algorithm is applied to an IEEE test network, for which sensitivity analysis is performed to determine how the parameters of the ES can be selected so that the algorithm performs in an effective way. Case studies show fairly promising results and the robustness of the proposed method.

On the finite element modeling of fatigue crack growth in pressurized cylindrical shells

A methodology for the computational modeling of the fatigue crack growth in pressurized shell structures, based on the finite element method and concepts of Linear Elastic Fracture Mechanics, is presented. This methodology is based on that developed by Potyondy [Potyondy D, Wawrzynek PA, Ingraffea, AR. Discrete crack growth analysis methodology for through crack in pressurized fuselage structures. Int J Numer Methods Eng 1995;38:1633-1644], which consists of using four stress intensity factors, computed from the modified crack integral method, to predict the fatigue propagation life as well as the crack trajectory, which is computed as part of the numerical simulation. Some issues not presented in the study of Potyondy are investigated herein such as the influence of the crack increment size and the number of nodes per element (4 or 9 nodes) on the simulation results by means of a fatigue crack propagation simulation of a Boeing 737 airplane fuselage. The results of this simulation are compared with experimental results and those obtained by Potyondy [1]. (C) 2008 Elsevier Ltd. All rights reserved.

Quantification of MgO surface excess on the SnO(2) nanoparticles and relationship with nanostability and growth

In this work, we experimentally showed that the spontaneous segregation of MgO as surface excess in MgO doped SnO(2) nanoparticles plays an important role in the system`s energetics and stability. Using Xray fluorescence in specially treated samples, we quantitatively determined the fraction of MgO forming surface excess when doping SnO(2) with several different concentrations and established a relationship between this amount and the surface energy of the nanoparticles using the Gibbs approach. We concluded that the amount of Mg ions on the surface was directly related to the nanoparticles total free energy, in a sense that the dopant will always spontaneously distribute itself to minimize it if enough diffusion is provided. Because we were dealing with nanosized particles, the effect of MgO on the surface was particularly important and has a direct effect on the equilibrium particle size (nanoparticle stability), such that the lower the surface energy is, the smaller the particle sizes are, evidencing and quantifying the thermodynamic basis of using additives to control SnO(2) nanoparticles stability. (C) 2010 Elsevier B.V. All rights reserved.

THE VANISHING DISCOUNT APPROACH FOR THE AVERAGE CONTINUOUS CONTROL OF PIECEWISE DETERMINISTIC MARKOV PROCESSES

This work is concerned with the existence of an optimal control strategy for the long-run average continuous control problem of piecewise-deterministic Markov processes (PDMPs). In Costa and Dufour (2008), sufficient conditions were derived to ensure the existence of an optimal control by using the vanishing discount approach. These conditions were mainly expressed in terms of the relative difference of the alpha-discount value functions. The main goal of this paper is to derive tractable conditions directly related to the primitive data of the PDMP to ensure the existence of an optimal control. The present work can be seen as a continuation of the results derived in Costa and Dufour (2008). Our main assumptions are written in terms of some integro-differential inequalities related to the so-called expected growth condition, and geometric convergence of the post-jump location kernel associated to the PDMP. An example based on the capacity expansion problem is presented, illustrating the possible applications of the results developed in the paper.

A positive growth response to NaCl applications in Eucalyptus plantations established on K-deficient soils

Contrasting responses of Eucalyptus trees to K fertilizer applications have been reported on soils with low K contents. A complete randomized block experiment was set up in Brazil to test the hypothesis that large atmospheric deposits of NaCl in coastal regions might lead to a partial substitution of K by Na in Eucalyptus physiology and enhance tree growth. Treatments with application of 1.5, 3.0, 4.5 kmol K ha(-1) (K(1.5), K(3.0), 1(4.5, respectively) as KCl, 3.0 kmol K ha(-1) applied as K(2)SO(4), 3.0 kmol Na ha(-1) (Na(3.0)) as NaCl commercialized for cattle feeding, and a mixture of 1.5 kmol K + 1.5 kmol Na ha(-1) (K(1.5) + Na(1.5)) were compared to a control treatment (C) with no K and Na applications. All the plots were fertilized with large amounts of the other nutrients. A positive effect of NaCl applications on the growth of E. grandis trees was observed. NaCl and KCl additions in treatments Na(3.0) and K(3.0) increased above-ground biomass by 56% and 130% three years after planting, respectively, in comparison with the C treatment. By contrast, accumulated litterfall up to age 3 years was not significantly modified. NaCl applications in the Na(3.0) treatment significantly increased Na accumulation in above-ground tree components but did not modify K accumulation, whatever the sampling age. A partial substitution of K by Na in tree physiology, as observed for various agricultural crops, might explain this behaviour. Our results suggest the possibility of applying inexpensive K fertilizers, which are less purified in Na, and explain why high yields are achieved without K fertilizer applications in areas with large dry depositions of marine aerosols. Further investigations are necessary to identify the processes involving Na in Eucalyptus tree physiology. (C) 2009 Elsevier B.V. All rights reserved.

Native tree seedling growth when fertilized with different amounts of dry sewage sludge and mineral fertilizer

The increasing volume of urban sewage nowadays generates considerable amount of sludge to be disposed of. One environmentally adequate destination could be the application of treated and stabilized sludge (biosolids) to forest plantations as fertilizer and soil conditioner. The purpose of this study was to analyze the feasibility of applying sewage sludge, evaluating its effects on native tree seedlings. The species evaluated were aroeira-pimenteira (Schinus terebinthifolia Raddi), cabreuva-vermelha (Myroxy-Ion peruiferum L. f.), pau-de-viola (Cytarexyllum myrianthum Cham), unha-de-vaca (Bauhinia forficata Link), which are usually planted in forest restoration. Seedlings were cultivated in pots, containing a volume of 4 dm(3) of soil, within a greenhouse. The study was developed in the proximity of Campinas, SP, Brazil, and installed in November, 2003. The design was entirely randomized including seven treatments: control; mineral fertilization; and different doses of sewage sludge (biosolids) complemented with potassium, due to the low concentration of this element in the sludge produced by the wastewater treatment plant of Barueri (Metropolitan region of Sao Paulo city). The results showed that the application of different dosages of biosolids promoted different responses in stem height and biomass production. The treatment with 20 g/dm(3) of dry sewage sludge promoted both the highest growth and the highest seedling biomass production, compared to the control treatment. All native tree species treated with the highest dosage of sewage sludge showed a growth similar to that of mineral fertilization. The seedlings of aroeira-pimenteira, pau-de-viola, and unha-de-vaca, all typical species of the initial succession in natural forest ecosystems, grew and produced more biomass than cabreuva-vermelha, a typical species of the final forest succession.

Sugar and ethanol production as a rural development strategy in Brazil: Evidence from the state of Sao Paulo

Sugar and ethanol production are key components of Brazil`s rural development and energy strategies, yet in recent years sugar production has been widely criticized for its environmental and labor practices. This study examines the relationship between rural development and sugarcane, ethanol, and cattle production in the state of Sao Paulo. Our results suggest that the value added components of sugarcane production, which include sugar refining and ethanol production, may have a strong positive affect on local human development in comparison to primary agricultural production activities and other land uses. These results imply that sugar production, when accompanied by a local processing industry can stimulate rural development. However, this paper also highlights the significant environmental and social harms generated by the sugar industry at large, which may undermine its development benefits if not addressed. (C) 2011 Elsevier Ltd. All rights reserved.

Bioinsecticidal activity of Talisia esculenta reserve protein on growth and serine digestive enzymes during larval development of Anticarsia gemmatalis

Plants synthesize a variety of molecules to defend themselves against an attack by insects. Talisin is a reserve protein from Talisia esculenta seeds, the first to be characterized from the family Sapindaceae. In this study, the insecticidal activity of Talisin was tested by incorporating the reserve protein into an artificial diet fed to the velvetbean caterpillar Anticarsia gemmatalis, the major pest of soybean crops in Brazil. At 1.5% (w/w) of the dietary protein, Talisin affected larval growth, pupal weight, development and mortality, adult fertility and longevity, and produced malformations in pupae and adult insects. Talisin inhibited the trypsin-like activity of larval midgut homogenates. The trypsin activity in Talisin-fed larvae was sensitive to Talisin, indicating that no novel protease-resistant to Talisin was induced in Talisin-fed larvae. Affinity chromatography showed that Talisin bound to midgut proteinases of the insect A. gemmatalis, but was resistant to enzymatic digestion by these larval proteinases. The transformation of genes coding for this reserve protein could be useful for developing insect resistant crops. (C) 2010 Elsevier Inc. All rights reserved.

Inorganic elements in the fat bodies of Diatraea saccharalis (Lepidoptera: Crambidae) larvae parasitized by Cotesia flavipes (Hymenoptera: Braconidae)

Koinobiont parasitoids use several strategies to regulate the host`s physiological processes during parasitism. Although many aspects of host-parasitoid interactions have been explored, studies that attempted to assess the effects of parasitism on the availability of inorganic elements in the host are virtually nonexistent. Therefore, we aimed to evaluate the effects of parasitism on the concentrations of inorganic elements in the fat bodies of larvae of Diatraea saccharalis (Lepidoptera: Crambidae) during the development of the parasitoid Cotesia flavipes (Hymenoptera: Braconidae), by using total reflection X-ray fluorescence (TXRF). TXRF analysis allowed comparisons of the changes in the availability of the elements P. S. K, Ca, Cr, Fe, Ni, Cu, and Zn in the fat body tissues of D. saccharalis larvae parasitized by C. flavipes. Overall, the concentration of inorganic elements was higher early in parasitoid development (1 and 3 days after parasitism) compared to non-parasitized larvae, but much lower towards the end of parasitoid development (7 and 9 days after parasitism). Ca, K, and S were reduced after the fifth day of parasitism, which affected the total abundance of inorganic elements observed in the fat bodies of the parasitized hosts. The regulatory mechanisms or pathological effects related to the observed variation of the host inorganic elements induced by the parasitoid remain unknown, but there might be a strategy to make these elements available to the parasitoid larvae at the end of their development, when higher metabolic activity of the host fat body is required to sustain parasitoid growth. The observed variation of the host`s inorganic elements could also be related to the known effects of parasitism on the host`s immune response. (C) 2010 Elsevier Inc. All rights reserved.

Adenanthera pavonina TRYPSIN INHIBITOR RETARD GROWTH OF Anagasta kuehniella (LEPIDOPTERA: PYRALIDAE)

Anagasta kuehniella is a polyphagous pest that feeds on a wide variety of stored products. The possible roles suggested for seed proteinase inhibitors include the function as a part of the plant defensive system against pest via inhibition of their proteolytic enzymes. In this study, a trypsin inhibitor (ApTI) was purified from Adenanthera pavonina seed and was tested for insect growth regulatory effect. The chronic ingestion of ApTI did result in a significant reduction in larval survival and weight. Larval and pupal developmental time of larvae fed on ApTI diet at 1% was significantly longer; the larval period was extended by 5 days and pupal period was 10 days longer, therefore delaying by up to 20 days and resulting in a prolonged period of development from larva to adult. As a result, the ApTI diet emergence rate was only 28% while the emergence rate of control larvae was 80%. The percentage of surviving adults (%S) decreased to 62%. The fourth instar larvae reared on a diet containing 1% ApTI showed a decrease in tryptic activity of gut and that no novel proteolytic form resistant to ApTI was induced. In addition, the tryptic activity in ApTI -fed larvae was sensitive to ApTI. These results suggest that ApTI have a potential antimetabolic effect when ingested by A. kuehniella. (C) 2010 Wiley Periodicals, Inc.

Effect of Calcium on the in vitro Growth of Aechmea blanchetiana (Baker) L. B. Smith Plantlets

This work investigated the influence of different concentrations of calcium on the growth of plantlets of the bromeliad Aechmea blanchetiana cultured in vitro. Seedlings of A. blanchetiana were axenically cultured in liquid Murashige and Skoog basal medium supplemented with different concentrations of calcium (Ca; 1.5, 3, 4.5, 6, or 12 mM) without growth regulators. The resulting plantlets were cultured under 93 mol m-2 s-1 illumination, 12 hour photoperiod regime and 25C 1 for 120 days with subculture to fresh identical media every 30 days. The addition of calcium at 9.38 mM to MS modified medium increased the production of fresh and dry mass of plantlets, whilst chlorine from calcium chloride dehydrate (CaCl2 2 H2O) in excess (3.35 mM) decreased both the fresh and dry mass of plantlets.

Simulation of irrigated Thanzania grass growth based on photothermal units, nitrogen fertilization and water availability

Simulation of irrigated Thanzania grass growth based on photothermal units, nitrogen fertilization and water availability. The mathematical model to predict the forage yield using photothennal units was utilized with success in Elephant grass, Thanzania and Brachiaria niziziensis in the absence of water stress and nitrogen stress. The aim of this study was to propose models to estimate the forage yield of Thanzania grass under different irrigation (25, 50,75, 100 e 125% of ETc) and nitrogen level in various regions of Brazil. As such, models were developed to estimate the dry matter production of Panicum maximum Jacq. frass cv Thanzania in different irrigation and nitrogen levels, using photothermal units. The models were adjusted to doses of 0, 30, 60, 110 and 270 kg of N ha(-1), doses were divided in applications after each evaluation, with a rest cycle of 35 days. The adjusted model presented good performance in predicting dry matter production of Thanzania grass, with r(2) = 0.9999. The results made it possible to verify that the proposed model can be used to predict forage production in different regions of Brazil. It can be estimated, with good precision. The production of Thanzania grass dry matter can be accurately estimated in specific places (in function of latitude and time of year), with the maximum and minimum temperature values.

Atmospheric Absorption of Fluoride by Cultivated Species. Leaf Structural Changes and Plant Growth

Fluoride (F) is an air pollutant that causes phytotoxicity. Besides the importance of this, losses of agricultural crops in the vicinity of F polluting industries in Brazil have been recently reported. Injuries caused to plant leaf cell structures by excess F are not well characterized. However, this may contribute to understanding the ways in which plant physiological and biochemical processes are altered. A study evaluated the effects of the atmospheric F on leaf characteristics and growth of young trees of sweet orange and coffee exposed to low (0.04 mol L(-1)) or high (0.16 mol L(-1)) doses of HF nebulized in closed chamber for 28 days plus a control treatment not exposed. Gladiolus and ryegrass were used as bioindicators in the experiment to monitor F exposure levels. Fluoride concentration and dry mass of leaves were evaluated. Leaf anatomy was observed under light and electron microscopy. High F concentrations (similar to 180 mg kg(-1)) were found in leaves of plants exposed at the highest dose of HF. Visual symptoms of F toxicity in leaves of citrus and coffee were observed. Analyses of plant tissue provided evidence that F caused degeneration of cell wall and cytoplasm and disorganization of bundle sheath, which were more evident in Gladiolus and coffee. Minor changes were observed for sweet orange and ryegrass. Increase on individual stomatal area was also marked for the Gladiolus and coffee, and which were characterized by occurrence of opened ostioles. The increased F absorption by leaves and changes at the structural and ultrastructural level of leaf tissues correlated with reduced plant growth.

Transmission of Methylobacterium mesophilicum by Bucephalogonia xanthophis for Paratransgenic Control Strategy of Citrus Variegated Chlorosis

Methylobacterium mesophilicum, originally isolated as an endophytic bacterium from citrus plants, was genetically transformed to express green fluorescent protein (GFP). The GFP-labeled strain of M. mesophilicum was inoculated into Catharanthus roseus (model plant) seedlings and further observed colonizing its xylem vessels. The transmission of this endophyte by Bucephalogonia xanthophis, one of the insect vectors that transmit Xylella fastidiosa subsp. pauca, was verified by insects feeding from fluids containing the GFP bacterium followed by transmission to plants and isolating the endophyte from C. roseus plants. Forty-five days after inoculation, the plants exhibited endophytic colonization by M. mesophilicum, confirming this bacterium as a nonpathogenic, xylem-associated endophyte. Our data demonstrate that M. mesophilicum not only occupy the same niche of X. fastidiosa subsp. pauca inside plants but also may be transmitted by B. xanthophis. The transmission, colonization, and genetic manipulation of M. mesophilicum is a prerequisite to examining the potential use of symbiotic control to interrupt the transmission of X. fastidiosa subsp. pauca, the bacterial pathogen causing Citrus variegated chlorosis by insect vectors.