Analysis of a sequential production of electricity,ice and drying of agricultural products by cascading geothermal energy

In this paper, it is presented an analysis for the sequential production of electricity, ice and drying of agricultural products, by the concept of cascade for medium and low temperature geothermal energy. To carry out the analysis, a set of practical assumptions for the integration of technologies operated by cascade method for geothermal energy were defined. The geothermal cascade is composed of three thermal levels, each one operating under different temperatures in decreasing form. Additionally, the thermal cascade is composed at the first level by an Organic Rankine Cycle (ORC) for electricity production. In the second thermal level, by an absorption refrigeration cycle for ice production, and in the third level includes a dehydrator for drying of agricultural products. The agricultural products considered for dehydration are: avocado, green chile and tomato. Once the main assumptions were set, five integration alternatives and five different modes of operation of the system were proposed. The alternatives have different features for the activation of the first thermal level of the cascade, different nominal capacities of electricity production, cold, and quantity of product to be dehydrated. Subsequently, a technical-economic analysis is carried out to obtain the performance and energy characteristics of the different thermal levels of the cascade, different modes of operation, carbon dioxide emissions, cost estimations and indicators of economic viability. The results indicate that the dehydration process improves drastically the economic profits of all alternatives, especially for dehydration of tomato, achieving simple payback periods of around one year, overall energy efficiency of up to 17.84% and greenhouse emissions reduction of 537.7 tonnes of CO₂ per year. Concerning the modes of operation, it was determined that the one based on only-electricity production is not desirable due to the worst energy and economic performance.     

Evaluation of EVA–PVAc blend behavior by 1‐D and 2‐D solid‐state NMR

Ethylene‐co‐vinyl acetate and poly(vinyl acetate) blends were prepared in different proportions by melting in a HAAKE Rheomix mixer. The blends were prepared at a fixed temperature, rotation rate, and processing time. High‐resolution solid‐state nuclear magnetic resonance was chosen to characterize the blends with respect to structure–mobility–compatibility employing magic angle spinning with cross polarization and high‐power hydrogen decoupling and the measurements of the proton spin–lattice relaxation time in the rotating frame (Tρ). The miscibility between polymer chains was also studied by two‐dimensional ¹H–¹³C shift correlation (HETCOR). © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 221–226, 1999     

The response of phenylalanine ammonia‐lyase,polyphenol oxidase and phenols to cold stress in the olive tree (Olea europaea L. cv. Picual)

BACKGROUND: In this study the activities of phenylalanine ammonia‐lyase (PAL) and polyphenol oxidase (PPO) and the concentrations of hydroxytyrosol, tyrosol and oleuropein in olive tree (Olea europaea L. cv. Picual) leaves were investigated before and after cold stress by freezing. The air temperature fell to below ?7 °C and, according to the specific field conditions, four categories of orchard were selected: not cold stressed (NS), lightly cold stressed (LS), moderately cold stressed (MS) and heavily cold stressed (HS). RESULTS: In LS and MS samples the PAL specific activity at saturated substrate concentration rose 4.8‐ and 1.9‐fold respectively compared with NS samples. In HS samples the PAL activity declined by 47% compared with NS samples. A low level of PAL protein was detected in all samples affected by cold stress. In LS, MS and HS samples the PPO specific activity at saturated substrate concentration was 1.9‐, 4.4‐ and 9.8‐fold higher respectively than in NS samples. K_m values also increased after cold stress. In MS and HS samples the concentration of oleuropein was 69 and 82% higher respectively than in NS samples, while the concentrations of hydroxytyrosol and tyrosol decreased. CONCLUSION: The response of PAL activity may be part of a recovery process of the olive leaf against cold stress, while the response of PPO and oleuropein may be part of an antioxidant protection mechanism. Copyright © 2009 Society of Chemical Industry     

Evaluation of culture media for enumeration of Lactobacillus acidophilus, Lactobacillus casei and Bifidobacterium animalis in the presence of Lactobacillus delbrueckii subsp bulgaricus and Streptococcus thermophilus

The study compared the growth capability of probiotic (Lactobacillus acidophilus La05, Lactobacillus casei Lc01 and Bifidobacterium animalis Bb12) and non-probiotic (Lactobacillus delbrueckii subsp bulgaricus and Streptococcus thermophilus) cultures on twenty-one culture media grouped according to selectivity: non-selective agars, selective agars without antibiotics and MRS agars containing different combinations of lithium chloride, cystein, bile salts and antibiotics. Four of these media were selected for quantitative enumeration of L. acidophilus La05, L. casei Lc01, and B. animalis Bb12. The best culture media and incubation conditions for enumeration of the probiotic cultures were: B. animalis: MRS agar with dicloxacillin, 37 °C or 42 °C, anaerobiosis; L. acidophilus: MRS agar with bile salts, 37 °C or 42 °C, aerobiosis; L. casei: MRS agar with lithium chloride and sodium propionate, 37 °C or 42 °C, aerobiosis or anaerobiosis. Plating on MRS with glucose replaced by maltose, 37 °C or 42 °C, anaerobiosis, will distinguish probiotic from non-probiotic cultures. For enumeration of each probiotic in a mixed culture, the following media and incubation conditions were recommended: B. animalis: 4ABC-MRS, 42 °C, anaerobiosis, L. acidophilus: LC medium, 42 °C, aerobiosis or anaerobiosis and L. casei: LP-MRS, 42 °C, aerobiosis or anaerobiosis. In all experiments, differences in counts using pour plating or surface plating were not significant (P ≤ 0.05).     

Determination of ultratrace levels of selenium in fruit and vegetable samples grown and consumed in Portugal

The selenium content in fruit and vegetable samples from two regions in Portugal were analysed using hydride generation atomic fluorescence spectrometry (HG-AFS) and radiochemical nuclear activation analysis (RNAA) – two analytical methods with very low limits of detection. The lower detection limits of HG-AFS, 3 μg kg⁻¹ and 8 μg kg⁻¹ (according to conditions used for digestion), and for RNAA, 10 μg kg⁻¹, meant that it was possible to determine selenium in samples previously analysed using the replicate sample instrumental nuclear activation analysis (RSINAA) with a higher detection limit associated.     

Comparison of net portal absorption with predicted flow of digestible amino acids: scope for improving current models?

This study was undertaken to determine the relationship between measured net portal absorptions (NPA) and flows of digestible essential amino acids (EAA) predicted with the National Research Council model (NRC, 2001) or the Cornell Net Carbohydrate and Protein System model (CNCPS, version 5.0.34). Net portal absorption data were obtained from 33 measurements of portal-arterial plasma EAA concentration differences among 8 treatments in lactating dairy cows, with plasma flow estimated from downstream dilution of para amino-hippurate. The predicted digestible flows from NRC (2001) related better than CNCPS to NPA observed in our studies, as shown by the lower standard errors on the slopes for all EAA and lower root mean prediction errors for all EAA except Met and Phe. However, the partitioning of the prediction error indicated a systematic underprediction (mean bias) for the NRC model (2001), with the exception of Ile. It is important to note that a relationship of unity was not expected, as discussed in the paper, because of losses of EAA through portal-drained viscera metabolism. A revised set of predictive equations for digestible EAA was obtained using a subset of data from NRC (2001) limited to trials conducted with dairy cows. This increased the predicted flows of digestible EAA by only 2%. Flows of digestible EAA were also estimated using a factorial approach, assuming an AA composition for each fraction of the duodenal flow estimated by NRC (undegradable, microbial, and endogenous proteins). This resulted in a slight improvement in the slope of the regression between predicted flows and measured NPA, but still yielded predicted digestive flows that were too low to support observed NPA. Finally, on the basis of literature values, increment of the digestibility of the undegradable fraction of forages and of microbial protein is suggested to improve the relationship between predicted digestible flows and NPA. Overall, this study indirectly confirms, across EAA, smaller losses through gut metabolism for His, Met, and Lys, intermediate losses for the branched-chain AA with the higher losses for Thr.     

Energy efficient design of building: A review

Energy saving is a high-priority in developed countries. For this reason, energy-efficient measures are being increasingly implemented in all sectors. The residential sector is responsible for an important part of the energy consumption in the world. Most of this energy is used in heating, cooling, and artificial ventilation systems.With a view to developing energy-efficient structures, this article provides an overview of building design criteria that can reduce the energy demand for the heating and cooling of residential buildings. These criteria are based on the adoption of suitable parameters for building orientation, shape, envelope system, passive heating and cooling mechanisms, shading, and glazing. An analysis was made of previous studies that evaluated the influence of these parameters on the total energy demand and suggested the best design options. This study is useful for professionals who are responsible for decision-making during the design phase of energy-efficient residential buildings.