Removal of fluoride from electronic industrial effluentby RO membrane separation

The electronics industry generates large amounts of fluoride-containing effluents. The objective of this studyis to study the feasibility of applying reverse osmosis (RO) membrane separation to reduce fluoride load to less than 1 kg/d. The effect of transmembrane pressure on the removal of fluoride ion has been investigated in detail, and the design parameters of a small RO separation unit were estimated. The present study indicated that the rejection of fluoride ion is typically higher than 98%, considering that the RO membrane was fully regenerated after each set of experiments. The effect of upstream concentration on the required mechanical pressure was determined by estimating the theoretical osmotic pressure of the feed solution. For industrial effluents, the process developed in this work allows us to reduce the treated volume from 6 m³/d to 0.36 m³/d without any pretreatment or adding additional compounds. The cost of the designed RO separation plant (€76,000) is much less than that of the conventional treatment (€533/m³) that deals mainly with volumes rather than specific     

Principal component analysis of the electricity consumption in residential dwellings

Data gathered from energy audits, phone surveys and smart meter readings are used to derive regression models of the electricity consumption of housing units in Oshawa (Ontario, Canada). The database used comprises 59 predictors, for 62 observations. To address the problem of multi-collinearities among the predictors and at the same time reduce the number of needed predictors, a methodology is developed based on the latent root regression technique of Hawkins [5]. Contrary to other variable selection techniques such as the stepwise method, the technique used in this paper allows an easy identification of alternative subsets. Using this technique, a reduction of 85% in the number of predictors is obtained, leaving only nine of them in the final subset. These nine variables are the number of occupants, the house status (owned or rented), the number of weeks of vacation per year, the type of fuel used in the pool heater, the type of fuel used in the heating system, the type of fuel used in the domestic hot water heater, the existence or not of an air conditioning system, the type of air conditioning system, and the number of air changes per hour at 50 Pa. A regression with these nine predictors leads to an R² of 0.79, with an adjusted R² of 0.75 and all regression coefficients statistically significant at the 95% confidence level.     

Long-term effect of continuous cropping of irrigated rice on soil and yield trends in the Sahel of West Africa

The effects of 18 years continuous cropping of irrigated rice on soil and yields were studied in two long-term fertility experiments (LTFE) at Ndiaye and Fanaye in the Senegal River Valley (West Africa). Rice was planted twice in a year during the hot dry season (HDS) and wet season (WS) with different fertilizer treatments. Soil organic carbon (SOC) under fallow varied from 7.1 g kg⁻¹ at Fanaye to 11.0 g kg⁻¹ at Ndiaye. Rice cropping maintained and increased SOC at Ndiaye and Fanaye, respectively and fertilizer treatments did not affect SOC. Soil available P and exchangeable K were maintained or increased with long-term application of NPK fertilizers. Without any fertilizer, yields decreased by 60 kg ha⁻¹ (1.5%) and 115 kg ha⁻¹ (3%) per year at Fanaye and Ndiaye, respectively. The highest annual yield decreases of 268 kg ha⁻¹ (3.6%) and 277 kg ha⁻¹ (4.1%) were observed at Fanaye and Ndiaye, respectively when only N fertilizer was applied. Rice yields were only maintained with NPK fertilizers supplying at least 60 kg N, 26 kg P and 50 kg K ha⁻¹. It was concluded that the double cropping of irrigated rice does not decrease SOC and the application of the recommended doses of NPK fertilizer maintained rice yields for 18 years.     

Occurrence of α-Eleostearic Acid in Parinarium excelsum and Parinarium macrophyllum Seed Oils

The seeds of Parinarium excelsum and P. macrophyllum (Rosaceae or Chrysobalanaceae) yield about 65-66% of oil. ¹³C NMR and gas chromatographic analyses show that these two oils have a high content in α-eleostearic acid, about 62% for P. excelsum and 33% for P. macrophyllum. These results indicate that α-eleosteatic acid can be used as chemotaxonomic tracer and are in agreement, from a chemical point of view, with authors which consider that Chrysobalanaceae constitute a family different from Rosaceae.     

Steam blanching effect on polyphenoloxidase,peroxidase and colour of mango (Mangifera indica L.) slices

The heat stability of peroxidase (POD) and polyphenoloxidase (PPO) was investigated in mango (Mangifera indica L.) slices, and the relative colour was studied after different steam blanching times. There was complete inactivation after 5 min for POD and 7 min for PPO. Steam blanching of 3 min gave residual activity of 2.85% and 8.33% for PPO and POD, respectively, and when compared with samples blanched for 5 min had no effect on colour over 20 days of storage. Correlation was found between activities of PPO, POD and colour change over 20 days. After 7 min steam blanching the browning index was stable but less than at 3 and 5 min because non-enzymic browning had occurred. This research suggests that yellowness (b) and lightness (L) values contribute positively to the browning index (BI), compared to redness (a).     

Real Estate Property Maintenance Optimization Based on Multiobjective Multidimensional Knapsack Problem

The real estate property maintenance problem (REPMP) deals with the problem of the maintenance of real estate property buildings’ components using a limited budget in a limited period to achieve multiple and often conflicting objectives. Maintenance of the components requires a multiannual maintenance action plan optimized simultaneously on different criteria relative to buildings’ maintenance objectives (the quality of service, client satisfaction, regulatory compliance, etc.) while respecting a predetermined budget. This article presents an innovative modeling of REPMP into a multiobjective multidimensional knapsack problem and its optimization using a generalization of the discrete multiobjective particle swarm optimization algorithm and the Pareto optimality. An application of this methodology using data from a real estate property of 22 buildings of a major French company is presented and discussed.     

Thermal and mechanical properties of polypropylene/wood‐flour composites

In this research, polypropylene/wood‐flour composites (WPCs) were blended with different contents of wood and/or maleated polypropylene (MAPP) and clay. We found that the addition of MAPP or clay in the formulation greatly improved the dispersion of the wood fibers in the composite; this suggested that MAPP or clay may have played the role of an adhesion promoter in the WPCs. The results obtained with clay indicate that it also acted as a flame retardant. The thermal tests carried out with the produced samples showed an increased crystallization temperature (T_c), crystallinity, and melting temperature (T_m) with wood loading. The increase of the two former parameters was explained by the incorporation of wood flour, which played the role of nucleating agent and induced the crystallization of the matrix polymer. On the other hand, the T_m increase was ascribed to the insulating properties of wood, which hindered the movement of heat conduction. The effects of UV irradiation on T_m and T_c were also examined. T_c increased with UV exposure time; this implied that UV degradation generated short chains with low molecular weight that could move easily in the bulk of the sample and, thus, catalyze early crystallization. The flexural strength and modulus increased with increasing wood‐flour content. In contrast, the impact strength and tensile strength and strain decreased with increasing wood‐flour content. All of these changes were related to the level of dispersion of the wood flour in the polymeric matrix. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Rupture of a sinus of Valsalva aneurysm into the right ventricle. A case report in the cardiology clinic at the University Hospital Center of Dakar]

Human cytolytic T lymphocytes specific for autologous Burkitt's lymphoma express the gamma, delta T cell receptor and recognize immunoglobulin idiotype in an MHC-unrestricted manner. Antibodies against a member of the heat shock protein 70 family inhibit this specific cytotoxicity, implicating these molecules in tumor recognition and antigen presentation. Such data is relevant to the design of novel immunotherapies for cancer and provides new insights into target recognition by gamma, delta T cells.     

Optimal design of a hybrid solar–wind-battery system using the minimization of the annualized cost system and the minimization of the loss of power supply probability (LPSP)

Potou is an isolated site, located in the northern coast of Senegal. The populations living in this area have no easy access to electricity supply. The use of renewable energies can contribute to the improvement of the living conditions of these populations. The methodology used in this paper consists in Sizing a hybrid solar–wind-battery system optimized through multi-objective genetic algorithm for this site and the influence of the load profiles on the optimal configuration. The two principal aims are: the minimization of the annualized cost system and the minimization of the loss of power supply probability (LPSP).To study the load profile influence, three load profiles with the same energy (94 kW h/day) have been used.The achieved results show that the cost of the optimal configuration strongly depends on the load profile. For example, the cost of the optimal configuration decreases by 7% and 5% going from profile 1 to 2 and for those ones going from 1 to 3.     

Study of the Development of Positive Streamers Along an Ice Surface

This paper presents the results of fundamental investigations on the inception and propagation of corona discharge on an ice surface stressed with a standard lightning impulse voltage. High-speed photography and photomultiplier techniques were used to observe and record the propagation of the streamers. The effects of several experimental parameters such as freezing water conductivity and HV rod electrode radius on the streamer inception parameters were investigated. Moreover, time to first streamer, inception voltage and corresponding field, as well as streamer propagation velocity and charge deposited by a streamer on ice surface were measured. The results are discussed and emphases are laid on the main factors influencing the development of positive streamers on ice surface.