Glasses in the SbPO4-WO3 system

Glasses in the binary system (100 - x)SbPO4-xWO3 (20 <= x <= 60, x in mol%) have been prepared and characterized. Differential thermal analysis (DTA) shows that the glass transition temperature, T-g increases from 412 degrees C, for samples containing 20 mol% of WO3 to 481 degrees C observed for glass containing 60 mol%. Sample containing 40 mol% in WO3 were observed to be the most stable against devitrification. The structural organization of the glasses has been studied by using Fourier transform infra-red (FTIR), Raman, P-31 Magic angle spinning (MAS) and spin echo nuclear magnetic resonance (NMR) spectroscopies. Results suggest two distinct networks comprising the glass structure, one with high SbPO4 content and the other characteristic of the highest WO3 content samples. The glasses present photochromic properties. Colour changes are observed for samples after exposure to ultraviolet or visible laser light. XANES, at L-1 absorption edge of tungsten, suggests partial reduction from W6+ to W5+ species during the laser irradiation. The photochromic effects and the colour changes, promoted by laser excitation, are reversible and easily removed by heat for during 1 h at 150 degrees C. Subsequent 'write/erase' cycles can be done without degradation of the glasses. (C) 2007 Elsevier B.V. All rights reserved.

Spinning reserve opportunity cost in hydroelectric plants

Starting from the deregulated process of the Electric Sector, there was the need to attribute responsibilities to several agents and to elaborate appropriate forms of remuneration of the services rendered by the same. One of the services of great importance within this new electric sector is the Ancillary Services. Among the various types of Ancillary Services, Spinning Reserve is a service necessary for maintaining the integrity of the transmission system from either generation interruptions or load variations. This paper uses the application of the Economic Dispatch theory with the objective of quantifies the availability of Spinning Reserve supply in hydroelectric plants. The proposed methodology utilizes the generating units as well as their efficiencies so as to attend the total demand with the minimum water discharge. The proposed methodology was tested through the data provided by the Água Vermelha Hydroelectric Power Plant. These tests permitted the opportunity cost valuation to the Spinning Reserve supply in hydroelectric plants. © 2005 IEEE.

Design of a labVIEW system applied to predictive maintenance

The implementation of vibration analysis techniques based on virtual instrumentation has spread increasingly in the academic and industrial branch, since the use of any software for this type of analysis brings good results at low cost. Among the existing software for programming and creation of virtual instruments, the LabVIEW was chosen for this project. This software has good interface with the method of graphical programming. In this project, it was developed a system of rotating machine condition monitoring. This monitoring system is applied in a test stand, simulating large scale applications, such as in hydroelectric, nuclear and oil exploration companies. It was initially used a test stand, where an instrumentation for data acquisition was inserted, composed of accelerometers and inductive proximity sensors. The data collection system was structured on the basis of an NI 6008 A/D converter of National Instruments. An electronic circuit command was developed through the A/D converter for a remote firing of the test stand. The equipment monitoring is performed through the data collected from the sensors. The vibration signals collected by accelerometers are processed in the time domain and frequency. Also, proximity probes were used for the axis orbit evaluation and an inductive sensor for the rotation and trigger measurement. © (2013) Trans Tech Publications, Switzerland.

Emergy assessment of tilapia cage farming in a hydroelectric reservoir

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

Influence of summertime mesoscale convective systems on the heat balance and surface mixed layer dynamics of a large Amazonian hydroelectric reservoir

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estimation of chlorophyll-a concentration and the trophic state of the Barra Bonita hydroelectric reservoir using oli/landsat-8 images

Reservoirs are artificial environments built by humans, and the impacts of these environments are not completely known. Retention time and high nutrient availability in the water increases the eutrophic level. Eutrophication is directly correlated to primary productivity by phytoplankton. These organisms have an important role in the environment. However, high concentrations of determined species can lead to public health problems. Species of cyanobacteria produce toxins that in determined concentrations can cause serious diseases in the liver and nervous system, which could lead to death. Phytoplankton has photoactive pigments that can be used to identify these toxins. Thus, remote sensing data is a viable alternative for mapping these pigments, and consequently, the trophic. Chlorophyll-a (Chl-a) is present in all phytoplankton species. Therefore, the aim of this work was to evaluate the performance of images of the sensor Operational Land Imager (OLI) onboard the Landsat-8 satellite in determining Chl-a concentrations and estimating the trophic level in a tropical reservoir. Empirical models were fitted using data from two field surveys conducted in May and October 2014 (Austral Autumn and Austral Spring, respectively). Models were applied in a temporal series of OLI images from May 2013 to October 2014. The estimated Chl-a concentration was used to classify the trophic level from a trophic state index that adopted the concentration of this pigment-like parameter. The models of Chl-a concentration showed reasonable results, but their performance was likely impaired by the atmospheric correction. Consequently, the trophic level classification also did not obtain better results.

Improvement of fungal arabinofuranosidase thermal stability by reversible immobilization

A gene encoding a-L-arabinofuranosidase (abfA) from Aspergillus niveus was identified, cloned, and successfully expressed in Aspergillus nidulans. Based on amino acid sequence comparison, the 88.6 kDa enzyme could be assigned to the GH family 51. The characterization of the purified recombinant AbfA revealed that the enzyme was active at a limited pH range (pH 4.0-5.0) and an optimum temperature of 70 degrees C. The AbfA was able to hydrolyze arabinoxylan, xylan from birchwood, debranched arabinan, and 4-nitrophenyl arabinofuranoside. Synergistic reactions using both AbfA and endoxylanase were also assessed. The highest degree of synergy was obtained after the sequential treatment of the substrate with endoxylanase, followed by AbfA, which was observed to release noticeably more reducing sugars than that of either enzyme acting individually. The immobilization of AbfA was performed via ionic adsorption onto various supports: agarose activated by polyethyleneimine polymers, cyanogen bromide activated Sepharose, DEAE-Sepharose, and Sepharose-Q The Sepharose-Q derivative remained fully active at pH 5 after 360 min at 60 degrees C, whereas the free AbfA was inactivated after 60 min. A synergistic effect of arabinoxylan hydrolysis by AbfA immobilized in Sepharose-Q and endoxylanase immobilized in glyoxyl agarose was also observed. The stabilization of arabinofuranosidases using immobilization tools is a novel and interesting topic. (C) 2012 Elsevier Ltd. All rights reserved.

Structure and Ionic Conductivity in the Mixed-Network Former Chalcogenide Glass System [Na2S](2/3)[(B2S3)(x)(P2S5)(1-x)](1/3)

Glasses in the system [Na2S](2/3)[(B2S3)(x)(P2S5)(1-x)](1/3) (0.0 <= x <= 1.0) were prepared by the melt quenching technique, and their properties were characterized by thermal analysis and impedance spectroscopy. Their atomic-level structures were comprehensively characterized by Raman spectroscopy and B-11, P-31, and Na-23 high resolution solid state magic-angle spinning (MAS) NMR techniques. P-31 MAS NMR peak assignments were made by the presence or absence of homonuclear indirect P-31-P-31 spin-spin interactions as detected using homonuclear J-resolved and refocused INADEQUATE techniques. The extent of B-S-P connectivity in the glassy network was quantified by P-31{B-11} and B-11{P-31} rotational echo double resonance spectroscopy. The results clearly illustrate that the network modifier alkali sulfide, Na2S, is not proportionally shared between the two network former components, B and P. Rather, the thiophosphate (P) component tends to attract a larger concentration of network modifier species than predicted by the bulk composition, and this results in the conversion of P2S74-, pyrothiophosphate, Na/P = 2:1, units into PS43-, orthothiophosphate, Na/P = 3:1, groups. Charge balance is maintained by increasing the net degree of polymerization of the thioborate (B) units through the formation of covalent bridging sulfur (BS) units, B S B. Detailed inspection of the B-11 MAS NMR spectra reveals that multiple thioborate units are formed, ranging from neutral BS3/2 groups all the way to the fully depolymerized orthothioborate (BS33-) species. On the basis of these results, a comprehensive and quantitative structural model is developed for these glasses, on the basis of which the compositional trends in the glass transition temperatures (T-g) and ionic conductivities can be rationalized. Up to x = 0.4, the dominant process can be described in a simplified way by the net reaction equation P-1 + B-1 reversible arrow P-0 + B-4, where the superscripts denote the number of BS atoms for the respective network former species. Above x = 0.4, all of the thiophosphate units are of the P-0 type and both pyro-(B-1) and orthothioborate (B-0) species make increasing contributions to the network structure with increasing x. In sharp contrast to the situation in sodium borophosphate glasses, four-coordinated thioborate species are generally less abundant and heteroatomic B-S-P linkages appear to not exist. On the basis of this structural information, compositional trends in the ionic conductivities are discussed in relation to the nature of the charge-compensating anionic species and the spatial distribution of the charge carriers.

Solid electrolytes for electrochromic devices based on reversible metal electrodeposition

Air conditioning and lighting costs can be reduced substantially by changing the optical properties of "intelligent windows." The electrochromic devices studied to date have used copper as an additive. Copper, used here as an electrochromic material, was dissolved in an aqueous animal protein-derived gel electrolyte. This combination constitutes the electrochromic system for reversible electrodeposition. Cyclic voltammetry, chronoamperometric and chromogenic analyses indicated that were obtained good conditions of transparency (initial transmittance of 70%), optical reversibility, small potential window (2.1 V), variation of transmittance in visible light (63.6%) and near infrared (20%) spectral regions. Permanence in the darkened state was achieved by maintaining a lower pulse potential (-0.16 V) than the deposition potential (-1.0 V). Increasing the number of deposition and dissolution cycles favored the transmittance and photoelectrochemical reversibility of the device. The conductivity of the electrolyte (10(-3) S/cm) at several concentrations of CuCl2 was determined by electrochemical impedance spectroscopy. A thermogravimetric analysis confirmed the good thermal stability of the electrolyte, since the mass loss detected up to 100 degrees C corresponded to water evaporation and decomposition of the gel started only at 200 degrees C. Micrographic and small angle X-ray scattering analyses indicated the formation of a persistent deposit of copper particles on the ITO. (C) 2012 Elsevier B.V. All rights reserved.

Odd homoclinic orbits for a second order Hamiltonian system

The aim of this paper is to find an odd homoclinic orbit for a class of reversible Hamiltonian systems. The proof is variational and it employs a version of the concentration compactness principle of P. L. Lions in a lemma due to Struwe.

A New Diminutive Species of Loricaria (Siluriformes: Loricariidae) from the Rio Paraguay System, Mato Grosso do Sul, Brazil

Loricaria coximensis. new species, is described from the Rio Paraguay basin, in Mato Grosso do Sul State, Brazil. It is distinguished from all other species of Loricaria, except L. holmbergi, L. lundbergi, L. parnahybae, and L. pumila by having abdominal plates confined to the pre-anal shield and posterior median abdominal area, usually loosely joined or separated by naked areas, pectoral girdle mostly naked, with isolated plates near base of pectoral fins and posterior to gill opening vs. abdominal plates well developed and tightly arranged across the entire median abdominal area, including the pectoral girdle. It is distinguished from these other four species by meristic counts and several morphometric proportions, particularly a broader head (19.4-21.3% SL vs. 14.1-19.1% SL). Loricaria coximensis becomes the third described paedomorphic species of Loricaria, along with L. nickeriensis and L. pumila, based on its small adult size (<100 mm SL), reduced number of lateral dermal plates, and incomplete abdominal plate development. The new species is presently known only from a limited section of the Rio Coxim, which has been severely impacted by a hydroelectric dam and widespread conversion of land for agriculture.

Photo-induced reversible assembly of colloidal polymer nanoparticles

Polymer nanoparticles functionalized on the surface with photo-responsive labels were synthesized. In a first synthetic step, polystyrene was copolymerized with the cross-linker divinylbenzene and poly(ethylene glycol) acrylate in a miniemulsion, to produce nano-sized spheres (~ 60 nm radius) with terminal hydroxyl groups, which were functionalized in a subsequent synthetic step with photo-responsive labels. For this purpose, two photo-active molecular structures were separately used: anthracene, which is well known to form covalently bonded dimers upon photo-excitation; and pyrene, which only forms short lived excited state dimers (excimers). Acid derivatives of these labels (9-anthracene carboxylic acid and 1-pyrene butyric acid) were bonded to the hydroxyl terminal groups of the nanoparticles through an esterification reaction, via the intermediate formation of the corresponding acid chloride.rnThe obtained labeled nanoparticles appeared to be highly hydrophobic structures. They formed lyophobic suspensions in water, which after analysis by dynamic light scattering (DLS) and ultramicroscopic particle tracking, appeared to equilibrate as a collection of singly dispersed nanoparticles, together with a few nanoparticle aggregates. The relative amount of aggregates decreased with increasing amounts of the surfactant sodium dodecyl sulfate (SDS), thus confirming that aggregation is an equilibrated state resulting from lyophobicity. The formation of such aggregates was corroborated using scanning electron microscopy (SEM). The photo-irradiation of the lyophobic aqueous suspensions of anthracene labeled nanoparticles (An-NP) resulted in the formation of higher aggregates, as evidenced by DLS and ultramicroscopy. The obtained state of aggregation could be reverted by sonication. The possibility to re-aggregate the system in subsequent photo-excitation and sonication cycles was established. Likewise, the photo-irradiation of lyophobic aqueous suspensions of pyrene-labeled nanoparticles (Py-NP) resulted in the formation of higher aggregates, as evidenced by DLS and ultramicroscopy. These appeared to remain aggregated due to hydrophobic interactions. This system could also be re-dispersed by sonication and re-aggregated in subsequent cycles of photo-excitation and sonication.

Targeting neuronal populations by AAV-mediated gene transfer for studying the endocannabinoid system

The cannabinoid type 1 (CB1) receptor is involved in a plethora of physiological functions and heterogeneously expressed on different neuronal populations. Several conditional loss-of-function studies revealed distinct effects of CB1 receptor signaling on glutamatergic and GABAergic neurons, respectively. To gain a comprehensive picture of CB1 receptor-mediated effects, the present study aimed at developing a gain-of-function approach, which complements conditional loss-of-function studies. Therefore, adeno-associated virus (AAV)-mediated gene delivery and Cre-mediated recombination were combined to recreate an innovative method, which ensures region- and cell type-specific transgene expression in the brain. This method was used to overexpress the CB1 receptor in glutamatergic pyramidal neurons of the mouse hippocampus. Enhanced CB1 receptor activity at glutamatergic terminals caused impairment in hippocampus-dependent memory performance. On the other hand, elevated CB1 receptor levels provoked an increased protection against kainic acid-induced seizures and against excitotoxic neuronal cell death. This finding indicates the protective role of CB1 receptor on hippocampal glutamatergic terminals as a molecular stout guard in controlling excessive neuronal network activity. Hence, CB1 receptor on glutamatergic hippocampal neurons may represent a target for novel agents to restrain excitotoxic events and to treat neurodegenerative diseases. Endocannabinoid synthesizing and degrading enzymes tightly regulate endocannabinoid signaling, and thus, represent a promising therapeutic target. To further elucidate the precise function of the 2-AG degrading enzyme monoacylglycerol lipase (MAGL), MAGL was overexpressed specifically in hippocampal pyramidal neurons. This genetic modification resulted in highly increased MAGL activity accompanied by a 50 % decrease in 2-AG levels without affecting the content of arachidonic acid and anandamide. Elevated MAGL protein levels at glutamatergic terminals eliminated depolarization-induced suppression of excitation (DSE), while depolarization-induced suppression of inhibition (DSI) was unchanged. This result indicates that the on-demand availability of the endocannabinoid 2-AG is crucial for short-term plasticity at glutamatergic synapses in the hippocampus. Mice overexpressing MAGL exhibited elevated corticosterone levels under basal conditions and an increase in anxiety-like behavior, but surprisingly, showed no changes in aversive memory formation and in seizure susceptibility. This finding suggests that 2 AG-mediated hippocampal DSE is essential for adapting to aversive situations, but is not required to form aversive memory and to protect against kainic acid-induced seizures. Thus, specific inhibition of MAGL expressed in hippocampal pyramidal neurons may represent a potential treatment strategy for anxiety and stress disorders. Finally, the method of AAV-mediated cell type-specific transgene expression was advanced to allow drug-inducible and reversible transgene expression. Therefore, elements of the tetracycline-controlled gene expression system were incorporated in our “conditional” AAV vector. This approach showed that transgene expression is switched on after drug application and that background activity in the uninduced state was only detectable in scattered cells of the hippocampus. Thus, this AAV vector will proof useful for future research applications and gene therapy approaches.

Reversible microbial colonization of germ-free mice reveals the dynamics of IgA immune responses

The lower intestine of adult mammals is densely colonized with nonpathogenic (commensal) microbes. Gut bacteria induce protective immune responses, which ensure host-microbial mutualism. The continuous presence of commensal intestinal bacteria has made it difficult to study mucosal immune dynamics. Here, we report a reversible germ-free colonization system in mice that is independent of diet or antibiotic manipulation. A slow (more than 14 days) onset of a long-lived (half-life over 16 weeks), highly specific anticommensal immunoglobulin A (IgA) response in germ-free mice was observed. Ongoing commensal exposure in colonized mice rapidly abrogated this response. Sequential doses lacked a classical prime-boost effect seen in systemic vaccination, but specific IgA induction occurred as a stepwise response to current bacterial exposure, such that the antibody repertoire matched the existing commensal content.

Transgenic system for conditional induction and rescue of chronic myocardial hibernation provides insights into genomic programs of hibernation

A key energy-saving adaptation to chronic hypoxia that enables cardiomyocytes to withstand severe ischemic insults is hibernation, i.e., a reversible arrest of contractile function. Whereas hibernating cardiomyocytes represent the critical reserve of dysfunctional cells that can be potentially rescued, a lack of a suitable animal model has hampered insights on this medically important condition. We developed a transgenic mouse system for conditional induction of long-term hibernation and a system to rescue hibernating cardiomyocytes at will. Via myocardium-specific induction (and, in turn, deinduction) of a VEGF-sequestering soluble receptor, we show that VEGF is indispensable for adjusting the coronary vasculature to match increased oxygen consumption and exploit this finding to generate a hypoperfused heart. Importantly, ensuing ischemia is tunable to a level at which large cohorts of cardiomyocytes are driven to enter a hibernation mode, without cardiac cell death. Relieving the VEGF blockade even months later resulted in rapid revascularization and full recovery of contractile function. Furthermore, we show that left ventricular remodeling associated with hibernation is also fully reversible. The unique opportunity to uncouple hibernation from other ischemic heart phenotypes (e.g., infarction) was used to determine the genetic program of hibernation; uncovering hypoxia-inducible factor target genes associated with metabolic adjustments and induced expression of several cardioprotective genes. Autophagy, specifically self-digestion of mitochondria, was identified as a key prosurvival mechanism in hibernating cardiomyocytes. This system may lend itself for examining the potential utility of treatments to rescue dysfunctional cardiomyocytes and reverse maladaptive remodeling.