Time Decay of the Activity of the Reduction Reaction of NO by CO on a Pd/Al2O3 Catalyst

An experimental study is made of the time decay of activity of the CO–NO reaction on a Pd/Al₂O₃ looking at the effect on reaction order and apparent activation energy. The optimum kinetics parameters fitting the steady state data at moderate pressures are determined. The time decay curves are analyzed through various catalyst deactivation models.     

Specific consumption of liquid biofuels in gasoline fuelled engines

Oxygenated fuels increase fuel consumption due to their low enthalpy of combustion; however, their high antiknock index renders them suitable for use in engines with a high compression rate, increasing their thermal yield. This study evaluated the performance of biorenewable oxygenated fuels (ethanol and isoamyl alcohol) and partially renewable fuels (ETBE: ethyl tert-butyl ether, TAEE: tert-amyl ethyl ether and di-TAE: di-tert-amyl ether) with high degree of purity and in mixtures with automotive gasoline, based on tests with Otto cycle engines. Among the oxygenated fuels evaluated here, di-TAE was found to present the best characteristics of performance, both individually and in mixtures with gasoline.     

Optimization of the grapes reception process

Neural Computing and Applications - Grapes reception is a key process in wine production. The harvest days are extremely challenging days in managing the reception of the grapes, as the winery...     

Characteristics of WWTP sludge after drying in greenhouse for agricultural purposes

The sludge generated by sewage treatment which meets regulatory standards can be used in agriculture. With this understanding, the focus of this study is the evaluation of the agricultural characteristics and inorganic substances in excess activated sludge, which was subjected to drying in a greenhouse. The variables (factor) evaluated during the drying process were: type of sludge (digested or not digested), addition of lime to the sludge, and the physical layout and rotation of sludge in the greenhouse. The parameters monitored for this assessment were moisture, volatile solids and pH. The greenhouse cover and sides were made of translucent plastic to allow the penetration of solar radiation and prevent water from entering. A impermeable floor was used. The sludge was generated in sewage treatment plants located in the metropolitan region of Grande Vitória, Espírito Santo, Brazil. The solar drying of wastewater sludge in a greenhouse presented satisfactory results.     

Ultrastructural characteristics of spermatogenesis in Pallas's mastiff bat, Molossus molossus (Chiroptera: Molossidae)

Despite the large number of species, their wide distribution, and unique reproductive characteristics, Neotropical bats have been poorly studied, and important aspects of the reproduction of these animals have not been elucidated. We made an ultrastructural analysis of spermatogenesis in Molossus molossus (Molossidae). The process of spermatogonial differentiation is similar to that found in other bats and is also relatively similar to that of Primates, with three main spermatogonia types: A(d), A(p), and B. Meiotic divisions proceed similarly to those of most mammals, and spermiogenesis is clearly divided into 12 steps, in the middle of the range known for bats (9-16 steps). Formation of the acrosome is similar to that known from other mammals; however, the ultrastructure of spermatozoa was found to have unique characteristics, including many wavy acrosomal projections on its surface, which seems to be specific for the family Molossidae. Comparing the ultrastructure of the spermatozoon of M. molossus with other bats already study, we observed that three characters vary: morphology of the outer dense fibers, of the perforatorium, and of the spermatozoon head. The great similarity of morphological characters between M. molossus and Platyrrhinus lineatus suggests that M. molossus is more closely related to the Phyllostomidae than to the Rhinolophidae and the Vespertilionidae.     

Shelf life of powdered Campomanesia adamantium pulp in controlled environments

The objective of this study was to evaluate the shelf life of powdered guavira pulp obtained by a foam mat drying process. The dehydrated guavira pulp was packed into low density polyethylene (LDPE) bags and stored under two controlled conditions: environmental (25 °C, RH 75%) and accelerated (35 °C, RH 90%) for 90 days. The shelf life was accompanied by carrying out the following analyses every 10 days: moisture content, water activity, vitamin C content, pH and titratable acidity. Vitamin C was the quality attribute used to determine the shelf life of the product, by determining its degradation kinetics as a function of storage time. The linear regression data showed that the vitamin C degradation reaction fitted the zero and first order kinetic models. The shelf life of the powdered guavira pulp under environmental conditions was approximately 49 days, and under accelerated conditions (35 °C) 45 days. The Q10 was equal to 1.09, predicting a shelf life similar to that found under environmental conditions. The moisture content for these conditions was 10.0% e 5.4% for 35 °C and 25 °C, respectively. The above demonstrate the efficiency of the accelerated test in predicting the shelf life of the product.     

Rheological performance of pectin-enriched products isolated from red beet (Beta vulgaris L. var. conditiva) through alkaline and enzymatic treatments

The rheological performance of pectin-enriched products extracted from red beet (Beta vulgaris L. var. conditiva) root by-products was evaluated in the present work. They were extracted through an alkaline pre-treatment with or without a subsequent enzymatic (hemicellulase or cellulase) hydrolysis at pH 5.2. Flow assays performed with 2.00% w/v-pectin aqueous systems showed pseudoplastic (flow index, n ≈ 0.4 or 0.8) or Newtonian (n = 1.0) behaviour after fitting of experimental data to Ostwald’s law, also showing poor thickening effect. When Ca²⁺ was added to water with the same pectin concentration, true gels developed as confirmed by the mechanical spectra obtained through dynamic assays. Junction zones of homogalacturonan (HG) side chains mediated by Ca²⁺ were able to build up rigid networks in water.Isolated pectins (2.00% w/v) were also used to constitute milk model systems. Whole and skimmed milk were used at two different concentrations. Milk systems showed more transient and weaker gel networks when compared to Ca²⁺-aqueous systems, and were associated to the formation of a [κ-casein?calcium cross linked low methoxyl pectin] complex dampened by the included milk fat globules. Relaxation spectra of pectin-milk systems were in general extended to large relaxation times (10⁴ s) for all isolated fractions studied, which is typical of structured systems. Since all pectin fractions showed very similar chemical composition and molecular weight (average value and distribution), it was suggested that some differences in the rheological performance of each pectin product came from the different length of arabinans and distribution of rhamnose kinks (RG-I, random coil) as well as from the length of demethylated HG chains (semi-flexible coils).The results of this research show that the pectin-enriched fractions isolated from red beet root wastes are useful as additives in food formulation.     

Remote sensing of wetlands in South America: status and challenges

South America has a large proportion of wetlands compared with other continents. While most of these wetlands were conserved in a relatively good condition until a few decades ago, pressures brought about by land use and climate change have threaten their integrity in recent years. The aim of this article is to provide a bibliometric analysis of the available scientific literature relating to the remote sensing of wetlands in South America. From 1960 to 2015, 153 articles were published in 63 different journals, with the number of articles published per year increasing progressively since 1990. This rise is also paralleled by an increase in the contribution of local authors. The most intensively studied regions are the wetland macrosystems of South American mega-rivers: the Amazon and Paraná Rivers, along with the Pantanal at the headwaters of Paraguay River. Few studies spanned more than two countries. The most frequent objectives were mapping, covering all types of wetlands with optical data, and hydrology, focusing on floodplain wetlands with microwave data as the preferred data source. The last decade substantial growth reflects an increase in technological and scientific capacities. Nevertheless, the state of the art regarding the remote sensing of wetlands in South America remains enigmatic. Fundamental questions and guidelines which may contribute to the understanding of the functioning of these ecosystems are yet to be fully defined and there is considerable dispersion in the use of data and remote-sensing approaches.     

Optimal selection of soft sensor inputs for batch distillation columns using principal component analysis

In this paper, a novel methodology based on principal component analysis (PCA) is proposed to select the most suitable secondary process variables to be used as soft sensor inputs. In the proposed approach, a matrix is defined that measures the instantaneous sensitivity of each secondary variable to the primary variables to be estimated. The most sensitive secondary variables are then extracted from this matrix by exploiting the properties of PCA, and they are used as input variables for the development of a regression model suitable for on-line implementation.This method has been evaluated by developing a soft sensor that uses temperature measurements and a process regression model to estimate on-line the product compositions for a simulated batch distillation process. The identification of the optimal soft sensor inputs for this case study has been discussed with respect to the definition of the sensitivity matrix, the data sampling interval, the presence of measurement noise, and the size of the input set. The simulation results demonstrate that the proposed approach can effectively identify the size and configuration of the input set that leads to the optimal estimation performance of the soft sensor.