1000 resultados para Hydrogenionic potential
Resumo:
Brainstem auditory-evoked potential (BAEP) has been widely used for different purposes in veterinary practice and is commonly used to identify inherited deafness and presbycusis. In this study, 43 Boxer dogs were evaluated using the BAEP. Deafness was diagnosed in 3 dogs (2 bilateral and 1 unilateral) allowing the remaining 40 Boxers to be included for normative data analysis including an evaluation on the influence of age on the BAEP. The animals were divided into 2 groups of 20 Boxers each based on age. The mean age was 4.54 years (range, 1-8) in group I, and 9.83 years (range, 8.5-12) in group II. The mean latency for I, III, and V waves were 1.14 (±0.07), 2.64 (±0.11), and 3.48 (±0.10) ms in group I, and 1.20 (±0.12), 2.73 (±0.15), and 3.58 (±0.22) ms in group II, respectively. The mean inter-peak latencies for the I-III, III-V and I-V intervals were 1.50 (±0.15), 0.84 (±0.15), and 2.34 (±0.11) ms in group I, and 1.53 (±0.16), 0.85 (±0.15), and 2.38 (±0.19) ms in group II, respectively. Latencies of waves I and III were significant different between group I and II. For the I-III, III-V and I-V intervals, no significant differences were observed between the 2 groups. As far as we know, this is the first normative study of BAEP obtained from Boxer dogs.
Resumo:
The aim of this work is to study the conservation laws of continuous means mechanics and also to extend the Hamiltonian method for these kind of systems in order to valid for non-potential operators through variational approach. Besides illustrating with various examples of mechanical applications we also introduce in this work the new technique in order to treat such problems as the non-potential problem.
Resumo:
This thesis investigated building information modeling (BIM) from a material supplier’s point of view. The objective was to gain understanding about how a building material supplier could benefit from the growing use of BIM in the AEC (architectural, engineering and construction) industry. Increasing amount of inquiries related to BIM from customers and other interest groups had awoken target company’s interest towards BIM. This thesis acts as a pre-study for the target company related to potential of BIM. First of all BIM and its meaning from a material supplier’s point of view was defined based on a literature review. To reveal the potential benefits of BIM for a material supplier a questionnaire survey and in total of 11 interviews were conducted. Based on the literature review and analyzed results it came clear that BIM offers benefits also for material suppliers. Product libraries and material databases for BIM tools can act as an important marketing channel for material suppliers. Material suppliers could also utilize the information from the BIM models to schedule their deliveries more precisely and potentially even to schedule their own production. All this needs deeper cooperation between material suppliers, contractors and other stakeholders in the AEC industry. Based on the results also first steps for the target company to utilize the growing use of BIM were defined.
Resumo:
Value network has been studied greatly in the academic research, but a tool for value network mapping is missing. The objective of this study was to design a tool (process) for value network mapping in cross-sector collaboration. Furthermore, the study addressed a future perspective of collaboration, aiming to map the value network potential. During the study was investigated and pondered how to get the full potential of collaboration, by creating new value in collaboration process. These actions are parts of mapping process proposed in the study. The implementation and testing of the mapping process were realized through a case study of cross-sector collaboration in welfare services for elderly in the Eastern Finland. Key representatives in elderly care from public, private and third sectors were interviewed and a workshop with experts from every sector was also conducted in this regard. The value network mapping process designed in this study consists of specific steps that help managers and experts to understand how to get a complex value network map and how to enhance it. Furthermore, it make easier the understanding of how new value can be created in collaboration process. The map can be used in order to motivate participants to be engaged with responsibility in collaboration and to be fully committed in their interactions. It can be also used as a motivator tool for those organizations that intend to engage in collaboration process. Additionally, value network map is a starting point in many value network analyses. Furthermore, the enhanced value network map can be used as a performance measurement tool in cross-sector collaboration.
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The potential for seed bank formation of two perennial weed species, Ipomoea asarifolia (Desr.) Roem. & Schult. (Convolvulaceae) and Stachytarpheta cayennensis (Rich.) M. Vahl (Verbenaceae), both common in Amazonia , was evaluated in a degraded pasture area in eastern Brazilian Amazonia . Seeds were enclosed in nylon mesh packets and placed at the soil surface or buried at 5 or 10 cm deep. The number of viable seeds was recorded at 6, 10, 14 and 18 months after burial. Results showed that S. cayennensis has the ability to form persistent soil seed bank, while I. asarifolia seeds do not build up in the soil seed bank. For S. cayennensis and, to some extent, for I. asarifolia, seed survival was highest at greater burial depths.
Resumo:
The number of electric vehicles grows continuously and the implementation of charging electric vehicles is an important issue for the future. Increasing amount of electric vehicles can cause problems to distribution grid by increasing peak load. Currently charging of electric vehicles is uncontrolled, but as the amount of electric vehicles grows, smart charg-ing (controlled charging) will be one possible solution to handle this situation. In this thesis smart charging of electric vehicles is examined from electricity retailers` point of view. The purpose is to find out plausible saving potentials of smart charging, when it´s controlled by price signal. Saving potential is calculated by comparing costs of price signal controlled charging and uncontrolled charging.
Resumo:
The study evaluates the potential application of chemical substances, obtained from biogas plants` by-products. Through the anaerobic digestion process with biogas the large amount of digestate is produced. This digestate mainly consists on the organic matter with the high concentration of nutrients such as nitrogen and phosphorus. During ammonia stripping and phosphorus precipitation the products- ammonia water, ammonium sulfate, ammonium nitrate, ferrous phosphate, aluminum phosphate, calcium phosphate and struvite can be recovered. These chemicals have potential application in different industrial sectors. According to Finnish market and chemicals properties, the most perspective industrial applications were determined. Based on the data, obtained through the literature review and market study, the ammonia water was recognized as a most perspective recovered substances. According to interview provided among Finnish companies, ammonia water is used for flue gas treatment in SNCR technology. This application has a large scale in the framework of Finnish industrial sectors. As well nitrogen with phosphorous can be used as a source of nutrients in the biological wastewater treatment plants of paper mills.
Resumo:
The potential of three macrophytes, Azolla caroliniana, Salvinia minima, and Lemna gibba was assessed in this study to select plants for use in environmental remediation contaminated with atrazine. Experiments were carried out in a greenhouse over six days in pots containing Hoagland 0.25 strength nutritive solution at the following atrazine concentrations: 0; 0.01; 0.1; 1.0; 10.0 mg L-1. Decrease in biomass accumulation was observed in the three macrophytes, as well as toxic effects evidenced by the symptomatology developed by the plants which caused their deaths. The chlorosis and necrosis allowed to observe in the plants the high sensitivity of the three species to the herbicide. Plants presented low potential for removal of atrazine in solution when exposed to low concentrations of the herbicide. However, at the 10.0 mg L-1 atrazine concentration, L. gibba and A. caroliniana showed potential to remove the herbicide from the solution (0.016 and 0.018 mg atrazine per fresh mass gram, respectively). This fact likely resulted from the processes of atrazine adsorption by the dead material. The percentage of atrazine removed from the solution by the plants decreased when the plants were exposed to high concentrations of the pollutant. Azolla caroliniana, S. minima, and L. gibba were not effective in removing the herbicide from solution. The use of these species to remedy aquatic environments was shown to be limited.
Resumo:
The potential of three aquatic macrophytes, Azoll caroliniana, Salvinia minima and Lemna gibba, was evaluated in this work aimed at selection of plants to be used in remediation of environments contaminated by arsenic (As). The experiments were carried out in a greenhouse during six days in pots containing Hoagland solution (¼ ionic strength) at As concentrations of 0.5; 2.5 and 5.0 mg L-1. The three species showed greater As accumulation as the concentration of the metalloid in solution increased. However, a reduction was detected in fresh and dry mass gain when the plants were exposed to high As concentrations. The macrophytes showed differences in efficiency of removal of As in solution. A. caroliniana, S. minima and L. gibba accumulated, on average, 0.130; 0.200; and 1.397 mg mDM-1, respectively, when exposed to 5.0 mg L-1 of As. The macrophytes absorbed a greater quantity of As in solution with low phosphate content. The greater As concentration in L. gibba tissues lowered the chlorophyll and carotenoid contents as shown by the high chlorosis incidence. Lemna gibba also exhibited a decrease in leaf size, with the total chlorophyll and carotenoid synthesis not being affected by As in A. caroliniana. This species exhibited purplish leaves with high concentration of anthocyanin, whose presence suggested association to phosphate deficiency. Marginal necrosis occurred on S. minima floating leaves, with the released daughter-plants not showing any visual symptoms during the treatment. The percentage of As removed from the solution decreased when the plants were exposed to high concentrations of the pollutant. Among the three species studied, only L. gibba could be considered an As hyper-accumulator. The use of this plant species for remediation of aquatic environments was shown to be limited and requires further investigation.
Resumo:
A laboratory study was conducted to investigate the allelopathic effect of aqueous extracts of plant parts of Alternanthera philoxeroides and A. sessilis and soil incorporated residues on germination and seedling growth of rice (Oryza sativa). Aqueous extracts prepared from different plant parts of Alternanthera species delayed rice germination. Alternanthera philoxeroides and A. sessilis inhibited rice germination by 9-100% and 4-49%, respectively. Germination of rice seeds was reduced with increasing concentration of aqueous leaf extracts of both weed species. Early seedling growth (root and shoot lengths) and seedling vigor index were significantly reduced by 5% aqueous leaf extract compared with distilled water treated control. Germination, root and shoot lengths, root and shoot dry weights and seedling vigor index of rice were drastically reduced by 3 and 4% in residue infested soil compared with residue free soil. The inhibitory effect of A. philoxeroides in terms of germination and seedling growth of rice was greater than that of A. sessilis. Five percent aqueous leaf extract and 4% residue infested soil of A. philoxeroides caused complete failure of rice seed germination. Alternanthera philoxeroides contained water soluble phenolics, namely 4 hydroxy-3-methoxy benzoic acid (16.19 mg L-1) and m-coumaric acid (1.48 mg L-1), whereas Alternanthera sessilis was rich in chlorogenic acid (17.85 mg L-1), gallic acid (11.03 mg L-1) and vanillic acid (9.88 mg L-1). The study indicates that the allelopathic potential of Alternanthera species may play an important role in enhancing the invasiveness of these species and may suppress rice plants in the vicinity.
Resumo:
Imidazolinone herbicides present physicochemical characteristics that allow them to persist longer in environment, with increased chances of soil and water contamination, as well as carryover effects on subsequent crops. Phytoremediation is shown as a promising technique to decontaminate soils polluted by herbicides. The aim of this study was to assess the potential of some winter grown species in removing residuals from soils contaminated with imazethapyr + imazapic and imazapic + imazapyr, using pre-emergence to control weeds in summer grown rice fields. The experiment was conducted in a completely randomized design, with four replications. All species were subjected to herbicide application at different doses. Imazethapyr + imazapic and imazapyr + imazapic were applied at doses of 0.0, 1.0 and 2.0 L ha-1, and 0.0, 140 and 280 g ha-1, respectively, in pre-emergence of the species. Brassica napus and Festuca arundinaceae are not tolerant to herbicides, with 100% of phytotoxicity (plant death) for all doses assessed. The herbicide imazapyr + imazapic proved to be less selective, causing the highest phytotoxicity in the species tested. The most tolerant species to the herbicides was Vicia sativa, which may be the most suitable one for phytoremediation programs in areas contaminated with imazethapyr + imazapic and imazapyr + imazapic.
Resumo:
To investigate the allelopathic effect of Marsilea minuta against the germination and seedling growths of rice (Oryza sativa) and wheat (Triticum aestivum), germination bioassays were conducted in both Petri dish and soil cultures in laboratory conditions. Rice and wheat seeds were allowed to germinate in a 1, 2, 3, 4, and 5% (w/v) aqueous extract of whole plant and 2, 4, 6, and 8% (w/w) plant residue-incorporated soils of M. minuta. In Petri dish experiments, 5% (w/v) an aqueous extract of M. mimuta showed significantly lower germination percentages (18.8% and 56.3%), root lengths (0.9 and 4.5 cm), shoot lengths (3.3 and 12.4 cm), seedling lengths (4.1 and 25.0 cm), root dry weights (1.4 and 5.6 g), shoot dry weights (1.1 and 9.0 g), seedling biomasses (2.5 and 14.6 g), and seedling vigor indices (77.4 and 957.3) in rice and wheat, respectively. In pot experiments, the M. minuta residue infested soil, with 8% concentration, produced significantly lower germination percentages (25.3 and 37.5%), root lengths (2.7 and 6.1 cm), shoot lengths (6.2 and 16.5 cm), seedling lengths (8.9 and 22.6 cm), root dry weights (2.4 and 5.5 g), shoot dry weights (4.0 and 2.8 g), seedling biomasses (6.4 and 8.3 g), and seedling vigor indices (224.1 and 855.3) in rice and wheat, respectively. The highest phytotoxic action of 5% aqueous whole plant extract of M. minuta against test crops seem to be due to the presence of two potent phenolic compounds, namely p-coumaric acid (2.91 mg L-1) and m-coumaric acid (1.59 mg L-1) as determined by HPLC analysis.
Resumo:
The objective of this study was to assess the selectivity herbicide saflufenacil for two sweet sorghum hybrids, when sprayed in preemergence and postemergence, besides the use of Na-bentazon as a 'safener' for saflufenacil. Three experiments were conducted, in pots, maintained in an ambient condition (second and third experiments) and in a greenhouse (first experiment). In each experiment a completely randomized distribution was used, with four replicates. In the first (2 x 6 factorial) two hybrids of sweet sorghum (CVSW 80007 and CVSW 80147) and six dosages (0; 35; 52.5; 70; 87.5 and 105 g ha-1) of saflufenacil were studied, applied in preemergence of the plants. In the second (2 x 5 factorial) the same hybrids of sweet sorghum sprayed in postemergence with saflufenacil (0; 35; 52.5; 70 and 87.5 g h-1) were assessed. In the third (4 x 5 factorial) the association of Na-bentazon (0; 240; 480 and 720 g ha-1) to saflufenacil (0.35; 52.5; 70 and 87.5 g ha-1) was studied, when sprayed in postemergence on the sweet sorghum plants (CVSW 80007). Hybrid CVSW 80147 was more tolerant to saflufenacil than hybrid CVSW 800007, in preemergence or postemergence applications. The variables that best assessed the sensibility of the sweet sorghum to saflufenacil were number of emerged plants, for preemergence applications, and dry matter of stem for postemergence. Na-bentazon showed promise for use as 'safener' in postemergence applications of saflufenacil in sweet sorghum for dosages up to 70 g ha-1.
Exploring Herbicidal Potential of Aqueous Extracts of Some Herbaceous Plants Against Parthenium Weed
Resumo:
To assess the phytotoxic potential of Achyranthes aspera, Alternanthera philoxeroides, Datura metel and Rumex dentatus against Parthenium hysterophorus, 5% (w/v on dry weight basis) aqueous extracts from root, stem, leaf, flower and whole plant were tested through a Petri plate-based germination and pot-cultured seedling bioassays. Achyranthes aspera and A. philoxeroides inhibited parthenium weed germination more than extracts from other species. Whole plant, leaf and fruit extracts of A. aspera reduced the germination percentage (5%); leaf extract from A. philoxeroides caused lower germination index (0.4), higher mean germination time (14 d) and longer time to 50% germination (13.5 d) of parthenium weed. In the foliar spray bioassay, A. aspera reduced parthenium weed shoot growth more than the other species whereas R. dentatus caused more reduction in root growth. Whole plant extract from A. aspera caused maximum reduction in parthenium weed seedling vigor index (98%) and seedling biomass (96%). The aqueous extracts of A. aspera and A. philoxeroides contained higher concentrations of phenolics viz. gallic (16.9 mg L-1), caffeic (7.4 mg L-1), chromatotropic (63.8 mg L-1), p-coumaric (10.5 mg L-1), m-coumaric (3.1 mg L-1), syringic (9.21 mg L-1) and 4 hydroxy-3-methoxy benzoic (118.6 mg L-1) acids compared with extracts of the other two species tested.