Pore anisotropy and microporosity in nanostructured mesoporous solids

In this study, we carried out an investigation related to the determination of the anisotropy (b) of pores as well as the extent of microporosity (mic%) in various groups of nanostructured mesoporous materials. The mesoporous materials examined were fifteen samples belonging to the following groups of solids: MCM-48s, SBA-15s, SBA-16s, and mesoporous TiO2 anatases. The porosities of those materials were modified either during preparation or afterward by the addition of Cu(II) species and/or 3(5)-(2-pyridinyl) pyrazole (PyPzH) into the pores. The modification of porosity in each group took place to make possible the internal comparison of the b and mic% values within each group. The estimation of both the b and mic% parameters took place from the corresponding nitrogen adsorption-desorption isotherms. The new proposed method is able to detect a percentage of microporosity as low as a few percent, which is impossible by any of the methods used currently, without the use of any reference sample or standard isotherms. A meaningful inverse relationship is apparent between the b and mic% values, indicating that large values of b correspond to small values of mic%.

Slicing of soft, flexible solids with industrial applications

Thin slices of soft flexible solids have negligible bending resistance and hence store negligible elastic strain energy; furthermore such offcuts are rarely permanently deformed after slicing. Cutting forces thus depend only on work of separation (toughness work) and friction. These simplifying assumptions are not as restrictive as it might seem, and the mechanics are found to apply to a wide variety of foodstuffs and biological materials. The fracture toughness of such materials may be determined from cutting experiments: the use of scissors instrumented for load and displacement is a popular method where toughness is obtained from the work areas beneath load–displacement plots. Surprisingly, there is no analysis for the variation of forces with scissor blade opening and this paper provides the theory. Comparison is made with experimental results in cutting with scissors. The analysis is generalised to cutting with blades of variable curvature and applied to a commercial food cutting device having a rotating spiral plan form blade. The strong influence of the ‘slice/push ratio’ (blade tangential speed to blade edge normal speed) on the cutting forces is revealed. Small cutting forces are important in food cutting machinery as damage to slices is minimised. How high slice/push ratios may be achieved by choice of blade profile is discussed.

Texture development in ice cream - effects of adding cocoa solids

Dynamic rheological techniques can aid the understanding of the factors contributing to ice cream structure, though the data obtained differs from that deduced from destructive techniques. Studies have shown that ice cream systems are both strain- and frequency-dependent. Chocolate ice cream is normally more viscous than the equivalent vanilla ice cream during mix preparation and has more body on freezing. Ice creams were prepared with and without cocoa solids and frequency sweeps were made from 0.1 to 100 Hz at 0.1% strain. With rapidly frozen ice creams, both G' and G" increased in the presence of cocoa solids. Comparison of mixes made with and without low-fat cocoa powder or non-gelatinizing starch demonstrated a similar relationship, with higher apparent viscosities in those mixes containing either cocoa powder or the starch. The results were consistent with the cocoa particles adding to the effect of the fat globules in increasing viscosity.

A stress relaxation model for the viscoelastic solids based on the steady-state creep equation

Creep and stress relaxation are inherent mechanical behaviors of viscoelastic materials. It is considered that both are different performances of one identical physical phenomenon. The relationship between the decay stress and time during stress relaxation has been derived from the power law equation of the steady-state creep. The model was used to analyse the stress relaxation curves of various different viscoelastic materials (such as pure polycrystalline ice, polymers, foods, bones, metal, animal tissues, etc.). The calculated results using the theoretical model agree with the experimental data very well. Here we show that the new mathematical formula is not only simple but its parameters have the clear physical meanings. It is suitable to materials with a very broad scope and has a strong predictive ability.

Suspended and bed load sediment transport dynamics in two lowland UK streams—storm integrated monitoring

A great deal of work recently has focused on suspended and bedload sediment transport, driven primarily by interest in contaminant transfer. However, uncertainties regarding the role of storm events, macrophyte beds and interactions between the two phases of sediment still exist. This paper compares two study sites within the same catchment whose geology varies significantly. The differences in hydrology, suspended sediment (SS) transport and bed load transport that this causes are examined. In addition, a method to predict the mobilization of different size fractions of sediment during given flows is investigated using critical entrainment thresholds.

CONTRA: Improving the performance of dynamic investigations in natural abundance organic solids by mirror-symmetric constant-time CODEX

We present a minor but essential modification to the CODEX 1D-MAS exchange experiment. The new CONTRA method, which requires minor changes of the original sequence only, has advantages over the previously introduced S-CODEX, since it is less sensitive to artefacts caused by finite pulse lengths. The performance of this variant, including the finite pulse effect, was confirmed by SIMPSON calculations and demonstrated on a number of dynamic systems. (C) 2007 Elsevier Inc. All rights reserved.

Cyanobacteria and Cyanotoxin in the Billings Reservoir (São Paulo, SP, Brazil)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Caracterização de Efluente Têxtil e Proposta de Tratamento

Textile industry deals with a high diversity of processes and generation of wastewaters with a high content of pollutant material. Before being disposed of in water bodies, a pre-treatment of the effluent is carried out, which is sometimes ineffective. In order to be properly treated, physical and chemical properties of the effluent must be known, as well as the pollutant agents that might be present in it. This has turned out to be a great problem in the textile industry, for there is a variety of processes and the pollutant load is very diversified. The characterization of the effluent allows the identification of most critical points and, as a consequence, the most appropriate treatment procedure to be employed, may be chosen. This study presents the results obtained after characterizing the effluent of a textile industry that comprises knitting, dyeing and apparel sections, processing mainly polyester/cotton articles. In this work, twenty samples of the effluent were collected, and related to the changes in production. From the results, a statistical evaluation was applied, determined in function of the rate of flow. The following properties and pollutants agents were quantitatively analysed: temperature; pH; sulfides; chlorine; alcalinity; chlorides; cianides; phenols; color; COD (Chemical Oxygen Demand); TOC (Total Organic Carbon); oil and grease; total, fixed and volatile solids; dissolved, fixed and volatile solids; suspended, fixed and volatile solids; setteable solids and heavy metals such as cadmium, copper, lead, chromium, tin, iron, zinc and nickel. Analyses were carried out according to ABNT NBR 13402 norm, based upon Standard Methods for the Examination of Water and Wastewater. As a consequence, a global treatment proposal is presented, involving clean production practices as contaminant load reducer, followed by conventional (biological) treatment

Avaliação da eficiência de filtros anaeróbios na remoção de coliformes fecais e ovos de helmintos

The technology of anaerobic reactors for sanitary wastewater treatment has been extensively developed in Brazil, and today it is practically consolidated. They present several advantages, such as low construction and operating costs, and low sludge production, the anaerobic reactors are an attractive alternative to minimize problematic lack of basic sanitation in urban areas, and also of the rural areas. The anaerobic filters have been widely used in Brazil. It produces an effluent with low concentration of organic matter and solids suspended, besides conserving the nutrients, therefore, it is good for use in irrigation, but the practice must be associated with knowledge of the pathogens presence. The main objective of this study was to evaluate the efficiency of anaerobic filters in removal faecal coliforms and helminth eggs, and to verify if the effluent can be used for agricultural purposes, according to the World Organization of Health (WHO, 1989). The protocol used to enumerate helminths eggs was the modified Bailenger method, (Ayres and Mara, 1996) recommended by WHO for evaluation of raw effluent and treated effluent. The membrane filtration method was utilized to determine the concentrations of faecal coliforms. Three different systems of sewer treatment composed by anaerobic filters were analyzed. The results, in a general analysis, showed that all the researched systems reached a larger removal than 93% to helminth eggs, resulting in an effluent with smaller average than 1 egg/L. One of these systems, Sistema RN, reached a larger removal than 99%, confirming the good performance of the anaerobic filters in removal helminths eggs. Even with low concentrations of eggs in the influent, the filters were capable to remove this parameter efficiently. About faecal coliforms, it was observed for all the researched systems an effluent with 106 CFU/100mL. The high concentrations to faecal coliforms in the effluent just allow reuse for restricted irrigation, in agreement with the guidelines of WHO. Although the researched systems have not removed faecal coliforms efficiently, the results indicated a good efficiency of the anaerobic filters in removal helminth eggs

Estudos dos aspectos qualitativos e quantitativos da água e do sedimento no baixo curso do Rio Pitimbu (RN)

Urban growth of metropolitan areas has produced impacts of considerable importance on environment and water resources. Such impacts are in general associated with human activities, such as basin area uncontrolled development. In this context, Pitimbu river watershed, located at Natal metropolitan area, has been affected by uncontrolled development caused by urban expansion. Indeed, such effects have been reflected on water quantity and quality, which may produce social consequences. Pitimbu river is an important water supplier for human consumption, actually supplying a 2600 m3/h water discharge. This study aims to analyze the qualitative and quantitative aspects of water and sediment on Pitimbu river lowland portion. For this purpose, physical-chemical water properties were analyzed, and sediment macro invertebrates benthonic were monitored in two cross sections in a period between November 8th, 2007 and October 3rd, 2008. Monitoring methodology consisted of water and sediment sampling for laboratory analysis. Water quality analysis included Dissolved Oxygen, Oxygen Biochemical Demand, Nitrate, pH and Alkalinity, Suspended and Total Solids. The analysis of heavy metals in the sediment included Cadmium, Cobalt, Copper, Chrome, Silver and Nickel. Dry season water discharge data were measured and used to adjust recession function parameters, whose values reveal quick recession and strong river-aquifer unconfined interaction. Water quality analysis revealed the absence of degradation by organic composites. However, DO and BOD levels indicate that more consistent results could be provided if sampling time interval were reduced. Biomonitoring showed signs of aquatic ecosystem degradation by the absence of sensitive and abundance of resistant benthic organisms. Obtained results demonstrate the urgent need of effective management measures to provide environmental protection. The increase of environmental degradation will certainly make impracticable the use of water for human consumption

Desempenho de reatores aeróbios de leito fluidizado com circulação interna na remoção de matéria carbonácea tratando diferentes águas residuárias

The organic matter. (OM) removal efficiency in the biochemical oxygen demand (BOD) and chemical oxygen demand (COD) forms for domestic wastewater and semi-intensive fish culture effluents by using three phase aerobic fluidized bed reactors with circulation in concentric tubes was studied. Three different ratios between external and internal areas by different internal diameter configurations (100, 125 and 150mm) to the same external diameter of 250mm were used; sand for filters and granulated activated carbon were used as supporting media. The reactors were tested for three hydraulic retention times: 11.5min to the R100, and 3h for the R125 and R150 reactors. The results demonstrated that this kind of reactors had good performance in the BOD and COD removal for different concentrations of waste waters. BOD mean removal efficiencies obtained were: 47% at the R100 reactor, 57% and 93% of raw and filtered BOD respectively at R125, 48 and 89% of raw and filtered BOD at R150. The COD mean calculated removal efficiencies were: 75% at the R100 reactor, 56 and 86% of raw and filtered COD at R125, and 54 and 86% of raw and filtered COD at R150. In the case of domestic wastewater it is necessary to provide a solids removal system at the reactor outflow in order to increase the removal of suspended OM from the final effluent.

Electrofluid dynamic (EFD) energy conversion in gas flows with suspended nanoparticles

This work presents simulations of the Electrofluid Dynamic energy conversion process in slender channel devices having very small particles (in both micro and nano scales) as charge carriers. Solutions are discussed for a system composed by coupled differential equations, which includes the equation for the total current along the channel, the equations for total energy and momentum of the mixture (gas and solid particles), the continuity equation and the equations for energy and momentum of a single particle. Results for suspended particles of higher diameters have been previously published in the Literature, but the simulations here presented exhibit an appreciable increase in the values for output currents.

Electrofluid dynamic (EFD) energy conversion in gas flows with suspended nanoparticles

This work presents simulations of the Electrofluid Dynamic energy conversion process in slender channel devices having very small particles (in both micro and nano scales) as charge carriers. Solutions are discussed for a system composed by coupled differential equations, which includes the equation for the total current along the channel, the equations for total energy and momentum of the mixture (gas and solid particles), the continuity equation and the equations for energy and momentum of a single particle. Results for suspended particles of higher diameters have been previously published in the Literature, but the simulations here presented exhibit an appreciable increase in the values for output currents.

Tratamento de águas residuárias de suinocultura em reator UASB e filtro anaeróbio em série seguidos de filtro biológico percolador

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