Abstract Despite the great diversity, economic and environmental importance of limnic mollusks, the group is still little investigated in the Brazilian semiarid region, especially in the state of Piauí. Thus, this work aims to gather information on the diversity of limnic mollusks in the Brazilian Northeast and the semiarid region, including new records for the state of Piauí, northeastern Brazil. For this, collections in the urban perimeter of the Itaim and Guaribas Rivers, municipalities of Itainópolis, and Picos, respectively, between October 2017 and September 2019. Besides, a literature review was conducted on studies of malacofauna in the Northeast and the Brazilian semiarid region. A total of 11 species from the classes Gastropoda and Bivalvia were collected on the rivers of Piauí, being the first record of Uncancylus concentricus for the Northeast region. For lotic environments in the state of Piauí, Drepanotrema schubarti, Pomacea canaliculata, Pisidium dorbignyi and Stenophysa marmorata were registered for the first time. Then, it was possible to verify that the Northeast of Brazil has 71 species registered, of which 34 occur in the semiarid. The diversity of species surveyed and the first record of the occurrence of several of them for the semiarid region demonstrate the importance of expanding studies involving this group to other areas. The present study is the first to gather and increase the information available on the fauna of limnic mollusks for the Northeast and Brazilian semiarid regions. The information gathered here may contribute to future research and to the species conservation and the environments they occupy, especially considering the presence of non- native and vector species.

The Medium-Term Operation Planning (MTOP) of hydrothermal systems aims to define the generation for each power plant, minimizing the expected operating cost over the planning horizon. Mathematically, this task can be characterized as a linear, stochastic, large-scale problem which requires the application of suitable optimization tools. To solve this problem, this paper proposes to use the Nested Decomposition, frequently used to solve similar problems (as in Brazilian case), and Progressive Hedging, an alternative method, which has interesting features that make it promising to address this problem. To make a comparative analysis between these two methods with respect to the quality of the solution and the computational burden, a benchmark is established, which is obtained by solving a single Linear Programming problem (the Deterministic Equivalent Problem). An application considering a hydrothermal system is carried out.

This paper examines the frequencies of mammal roadkill in two adjacent biogeographic ecoregions (Atlantic Forest and Cerrado) of Brazil. Mammals were recorded during a seven-year period and over 3,900 km of roads, in order to obtain data for frequencies of species in habitats (sites) and frequencies of species killed by cars on roads. Sites (n = 80) within ecoregions (Cerrado, n = 57; Atlantic Forest, n = 23) were searched for records of mammals. Species surveyed in the entire region totaled 33, belonging to nine orders and 16 families. In the Cerrado, 31 species were recorded in habitats; of these, 25 were found dead on roads. In the Atlantic Forest ecoregions, however, we found 21 species in habitats, 16 of which were also found dead on roads. There was no overall significant difference between ecoregions for frequencies of occurrence in habitats or for roadkills, but there were differences between individual species. Hence, anteaters were mostly recorded in the Cerrado ecoregion, whereas caviomorph rodents tended to be more frequent in the Atlantic Forest ecoregion (seen mainly by roadkills). The greater number of species (overall and threatened) and the greater abundance of species records in the Cerrado suggest that this ecoregion has a greater biodiversity and is better conserved than the Atlantic Forest ecoregion, in the state of Mato Grosso do Sul, south-western Brazil.

A extração no ponto nuvem (CPE) foi realizada em duas etapas seqüenciais para a determinação de elementos traço em soro humano, sangue animal e dieta alimentar por espectrometria de massas com fonte de plasma indutivamente acoplado. A primeira CPE foi realizada adicionando dietil-ditiofosfato, Triton® X-114 seguida de aquecimento a 40 ºC, centrifugação e esfriamento a 0 ºC. A fase rica em surfactante foi separada para determinar Cd, Pb e Cu pela técnica de quantificação por diluição isotópica. As medidas das razões isotópicas foram caracterizadas por RSD < 0.7%. O pH da solução empobrecida em surfactantante foi ajustado entre 4 e 5 antes da adição de 4-(2-pirilidazo)resorcinol, Triton® X-114 e seguiram-se os procedimentos para atingir o ponto nuvem. Na segunda fase rica em surfactante extraída foram quantificados Co e Ni pelo método de adições de padrão com RSD < 2%. Recuperações entre 85 a 96% foram obtidas para todos os elementos. A exatidão foi aferida pela análise de materiais de referência com valores recomendados e certificados.

A two-step sequential cloud point extraction (CPE) of trace elements from small sample volumes of human serum, animal blood, and food diet is proposed to gain analytical information in the analysis by inductively coupled plasma mass spectrometry. The first CPE was attained by adding O,O-diethyldithiophosphate, the non ionic surfactant Triton® X-114 followed by heating at 40 ºC, centrifugation and cooling at 0 ºC. The resulting surfactant-rich phase was separated to determine Cd, Pb and Cu by isotope dilution. Isotope ratio measurements presented RSD < 0.7%. The residual surfactant-poor phase solution had the pH adjusted in the range 4 to 5 before the chelating reagent, 4-(2-pyridylazo) resorcinol plus surfactant Triton® X-114 were added followed by the sequence to attain the CPE. Co and Ni were quantified in the second extracted surfactant-rich phases by standard additions method with RSD < 2%. Recoveries from 85 to 96% were obtained for all elements. Analyzing reference materials with certified and recommended values assessed accuracy.

O problema da programação da operação energética visa definir quais unidades geradoras devem estar em operação para o atendimento à demanda e às demais restrições do sistema, ao longo do horizonte de estudo, de modo que o mínimo custo de operação seja encontrado. Matematicamente, trata-se de um problema não-linear, inteiro-misto e de grande porte, o que torna a sua solução uma tarefa desafiadora. Este artigo apresenta o uso da Relaxação Lagrangeana para decompor o problema da programação da operação em subproblemas menores e mais simples de serem solucionados. No esquema de decomposição utilizado, os subproblemas têm naturezas distintas e são construídos aproveitando-se as particularidades que cada um deles apresenta. Um dos subproblemas resultante do esquema de relaxação utilizado refere-se à alocação das unidades hidrelétricas. Para resolver esse subproblema, propõe-se um algoritmo de enumeração exaustiva do espaço de estados do problema. Cada combinação consiste na solução de problemas não-lineares restritos, resolvidos aqui por meio do método de Lagrangeano Aumentado. Tal método transforma cada problema restrito em uma série de subproblemas irrestritos, que por sua vez são solucionados por um algoritmo de Quase-Newton. O modelo computacional desenvolvido é aplicado a duas usinas hidrelétricas do sistema brasileiro, demonstrando-se a sua consistência e viabilidade prática.

The short-term operation planning problem aims to define the generation units should operate at minimum cost to fully supply the demand while meeting the system constraints over the study horizon. The problem is of a non-linear, integer-mixed, large scale optimization type, whose solution is a rather challenging task. This paper uses the Lagrangian Relaxation to decompose the original problem into simpler subproblems to be solved in sequence. In this decomposition, the subproblems are constructed taking advantage of their specific characteristics. One of the resulting subproblems of the relaxation scheme refers to the commitment of hydroelectric units. In order to solve this problem, an algorithm for exhaustive enumeration is proposed. This algorithm makes use of the Augmented Lagrangean method, which solves the resulting constrained nonlinear subproblems for each examined state. A Quasi-Newton method is used for the solution of the unconstrained subproblems resulting from the application of the Augmented Langrangean method. The proposed model is applied to two hydroelectric units of the Brazilian power system, demonstrating its consistency and practical feasibility.

We consider the optimal scheduling of hydropower plants in a hydrothermal interconnected system. This problem, of outmost importance for large-scale power systems with a high proportion of hydraulic generation, requires a detailed description of the so-called hydro unit production function. In our model, we relate the amount of generated hydropower to nonlinear tailrace levels; we also take into account hydraulic losses, turbine-generator efficiencies, as well as multiple 0-1 states associated with forbidden operation zones. Forbidden zones are crucial to avoid nasty phenomena such as mechanical vibrations in the turbine, cavitation, and low efficiency levels. The minimization of operating costs subject to such detailed constraints results in a large-scale mixed-integer nonlinear programming problem. By means of Lagrangian Relaxation, the original problem is split into a sequence of smaller and easy-to-solve subproblems, coordinated by a dual master program. In order to deal better with the combinatorial aspect introduced by the forbidden zones, we derive three different decomposition strategies, applicable to various configurations of hydro plants (with few or many units, which can be identical or different). We use a Sequential Quadratic Programming algorithm to solve nonlinear subproblems. We assess our approach on a real-life hydroelectric configuration extracted from the south sub region of the Brazilian hydrothermal power system.

Com o objetivo de avaliar o efeito do bebedouro pendular (BP) e do bebedouro alternativo (BALT), e de diferentes densidades (10 e 14 aves m-2) sobre o desempenho de 240 frangos de corte de 12 a 18, 19 a 38 e de 39 a 46 dias de idade, realizou-se este experimento em condições de temperatura média de 27,6 ºC e umidade relativa de 70,4%, no qual foi utilizado um delineamento inteiramente casualizado em esquema fatorial 2 x 2 (dois bebedouros x duas densidades), resultando em quatro tratamentos constituídos de cinco repetições de 10 aves. O BALT foi desenvolvido com base no conceito de amplo espaço de calha circular e alta profundidade de lâmina de água (5 cm) para permitir a imersão do bico e das faces da ave. Na alimentação das aves, foram utilizadas rações comerciais, cujo consumo (CR) caiu, enquanto a conversão alimentar (CA) melhorou, quando o BALT foi empregado de 12 a 18 dias. Não houve efeito do bebedouro sobre o CR, ganho de peso (GP) e CA no período total. A D14 (14 aves m-2) afetou o GP e o CR de 19 a 38 e de 39 a 46 dias e também no período total, mas a CA não foi alterada. O BALT não afeta o desempenho de frangos de corte, podendo ser usado como opção de baixo custo ao BP. A análise econômica pelo índice de rentabilidade relativa mostrou que o BALT e a D14 oferecem 1 e 5,9% de retorno a mais que o BP e a D10, (10 aves m-2) respectivamente.

The experiment was undertaken in conditions of average temperature of 27.6 ºC and relative humidity of 70.4%, with the objective to evaluate bell (BD) and alternative (ALT) water facility and stocking densities (SD) of 10 and 14 broilers m-2 (SD10 and SD14), on performance of 240 broiler chickens of 12 to 18, 19 to 38 and 39 to 46 days of age, allotted in boxes in a completely randomized design in 2 x 2 factorial arrangement (two types of drinking facility and two stocking densities), resulting in four treatments, each one with five replications of ten birds. The ALT was developed based on concept of wide and deep water level (5 cm) permitting not only the beak, but also entire face to be immersed. For the feeding of birds, commercial diets were utilized. The feed intake (FI) decreased, while the feed conversion ratio (FC) improved when the ALT was utilized from 12 to 18 days. There was no effect of drinking facility on FI, weight gain (WG) and FC in the entire period. The SD14 decreased FI and WG from 19 to 38 and from 39 to 46 days of age, and total period, but the FC was not affected. The ALT did not affect the broiler performance and may be used as an option of low cost in comparison with bell water facility. The economic analysis on income relative index basis showed that the ALT and SD14 offer 1 and 5.9% better income return than BD and SD10, respectively.

This paper presents the experimental characterization of hydrodynamics and gas-liquid mass transfer in a three-phase fluidized bed containing polystyrene and nylon particles. The influence of gas and liquid velocities on phase holdups and volumetric gas-liquid mass transfer coefficient was investigated for flow conditions similar to those applied in biotechnological process. The phase holdups were obtained by the pressure profile technique. The volumetric gas-liquid mass transfer coefficient was obtained adjusting the experimental concentration profiles of dissolved oxygen in the liquid phase with the predictions of the axial dispersion model. According to experimental results the liquid holdup increases with the gas velocity, whereas the solid holdup decreases. The gas holdup increases significantly with the increase in gas velocity, and it shows for the three-phase fluidized bed comparable values or larger than those of bubble column. The volumetric gas-liquid mass transfer coefficient increases significantly with an increase in the air velocity for both bubble column and fluidized beds. In addition, in the operational condition of high liquid velocity, the presence of low-density particles in the bed increased the gas-liquid mass transfer, and thus the volumetric mass transfer coefficient values obtained in the fluidized bed were comparable or larger than those of bubble column.