Mathematical modelling of mass transfer in the concentration polarisation layer of flat‐sheet membranes during clarification of pomegranate juice

Evaluation of membrane clarification of pomegranate juice showed that a cake layer is created at the beginning of the process. This evaluation was used as the basis for modelling the solute concentration in the concentration polarisation layer to control the fouling of the membrane. The model of changes in concentration as a function of time and distance (in its dimensionless form) was solved numerically using the Forward‐Time/Central‐Space (FTCS) method. Programming was performed using MATLAB software, and the predicted concentration on the membrane surface was compared with experimental data; the prediction fit well with the experimental data. The model showed that the solute concentration increased as distance to the membrane surface decreased, time increased, transmembrane pressure increased and velocity decreased. Also, the model matched the experimental data in that it showed the cake layer to be created in the early stages of the membrane clarification process.     

Optimization of the water-based road-marking paint by experimental design, mixture method

The main purpose of this research is formulating and optimizing a new road-marking paint which is an environmentally friendly product. This paint is produced with an emulsion of an acrylic copolymer and contains the least of the volatile organic compounds. The formulation and optimization procedure is carried out on the base of experimental design by the method of mixture in which the important paint properties are modeled by using special cubic model. The present method has the capability of investigation the effect of raw materials at different levels with fewer experiments than factorial and fractional factorial design.

In this research, the main parameters such as resin, pigment and filler were selected at different levels, and different samples were prepared by combination of additives and other required reagents. The properties of wet and dry films of the samples were determined using ASTM test methods. Different responses such as pigment volume concentration (PVC), latex critical pigment volume concentration (LCPVC), abrasion resistance, hardness, gloss, no pick up time and surface drying time, were selected as the objective functions of this study. By running DX6 software, using special cubic model and selection of desired range of end-use properties, the region of optimum paint formula was determined.

The accuracy of the model was examined by preparing a sample in optimized region and by determining its final properties, experimentally. The results exhibit a good agreement between the model and experimental measurements. This product was compared with commercial solvent based traffic paint and good quality was reported in end-use properties.     

Heat capacities of aluminium alloys

In the framework of the European COST 507 project the specific heat capacities of aluminium alloys and metal matrix composites based thereon have been measured between 20 and 520 °C by differential scanning calorimetry and stored in the databank THERSYST along with other thermophysical properties mainly drawn from literature. The curves show the influence of additional elements and reinforcements, of the fabrication process, thermomechanical treatment and scanning rate on the precipitation and dissolution kinetics of the various metastable phases and their relative amounts. The database may be used to select existing light alloys or elaborate new ones in view of specific technical applications.Dedicated to Professor Dr. Hans Löffler on the occasion of his 72nd birthday.     

Adult age differences in episodic memory: Further support for an associative-deficit hypothesis.

This study further tested an associative-deficit hypothesis (ADH; M. Naveh-Benjamin, 2000), which attributes a substantial part of older adults' deficient episodic memory performance to their difficulty in merging unrelated attributes-units of an episode into a cohesive unit. First, the results of 2 experiments replicate those observed by M. Naveh-Benjamin (2000) showing that older adults are particularly deficient in memory tests requiring associations. Second, the results extend the type of stimuli (pictures) under which older adults show this associative deficit. Third, the results support an ADH in that older adults show less of an associative deficit when the components of the episodes used are already connected in memory, thereby facilitating their encoding and retrieval. Finally, a group of younger adults who encoded the information under divided-attention conditions did not show this associative deficit. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Study and characterization of porous copper oxide produced by electrochemical anodization for radiometric heat absorber

The aim of this work is to optimize the different parameters for realization of an absorbing cavity to measure the incident absolute laser energy. Electrochemical oxidation is the background process that allowed the copper blackening. A study of the blackened surface quality was undertaken using atomic force microscopy (AFM) analysis and ultraviolet-visible-infrared spectrophotometry using a Shimadzu spectrophotometer. A two-dimensional and three-dimensional visualization by AFM of the formed oxide coating showed that the copper surfaces became porous after electrochemical etching with different roughness. This aspect is becoming more and more important with decreasing current density anodization. In a 2 mol L ^-1 of NaOH solution, at a temperature of 90°C, and using a 16 mA cm² constant density current, the copper oxide formed has a reflectivity of around 3% in the spectral range between 300 and 1,800 nm. Using the ‘mirage effect’ technique, the obtained Cu₂O diffusivity and thermal conductivity are respectively equal to (11.5 ± 0.5) 10 to 7 m² s^-1 and (370 ± 20) Wm^-1 K^-1. This allows us to consider that our Cu₂O coating is a good thermal conductor. The results of the optical and thermal studies dictate the choice of the cavity design. The absorbing cavity is a hollow cylinder machined to its base at an angle of 30°. If the included angle of the plane is 30° and the interior surface gives specular reflection, an incoming ray parallel to the axis will undergo five reflections before exit. So the absorption of the surface becomes closely near 0.999999.     

Dosimetric characteristic of a new 125I brachytherapy source

A new brachytherapy (125)I source has been investigated at Iranian Agricultural, Medical and Industrial Research School. Dosimetric characteristics [dose-rate constant Λ, radial dose function g(l)(r) and anisotropy function F(r,)] of IRA-(125)I were theoretically determined in terms of the updated AAPM task group 43 (TG-43U1) recommendations. Versions 5 and 4C of the Monte Carlo radiation transport code were used to calculate the dosimetry parameters around the source. The Monte Carlo calculated dose-rate constant of the (125)I source in water was found to be 92×10(-4) Gy h(-1) U(-1) with an approximate uncertainty of ±3 %. Brachytherapy seed model, 6711-(125)I, carrying (125)I radionuclides, was modelled and benchmarked against previously published values. Finally, the calculated results were compared with the published results of those of other source manufacturers.     

An experimental investigation into the performance of a domestic thermosyphon solar water heater under varying operating conditions

An experimental investigation has been carried out on a thermosyphon solar water heater. The system consisted of a flat-plate collector of 1.5 m² absorber area with 21 tubes/m width and storage tank of 125 litre capacity. Experiments were carried out for both cloudy and clear weather conditions in winter and summer. The hourly system performance was evaluated for all test conditions. The final mean tank temperature was measured daily which enabled the calculation of the possible contribution of solar energy for domestic hot water supply in Basrah, Iraq (latitude 30.76°N). The system was tested at both no-load and loading conditions. Intermittent and continuous load was imposed, and system performance was evaluated for each condition.     

Recycling value of building materials in building assessment systems

The selection of green building materials and products is by far the most controversial task in sustainable construction. Determining the merits of building materials and products in terms of their recycling value, which seems to be a simple matter, is a very controversial topic in building assessment systems. This paper suggests a method to assess energy savings by recycling building materials, which can be a potential indicator of recycling worth. The method takes account of material selection, construction and deconstruction technologies, and the frequency of recycling. The result of this study can be used in assessment tools as a factor separate from the embodied energy. Since embodied energy affects the potential recycling energy, another factor is defined, based on these two factors, in order to make it possible to compare and select materials correctly, based on their embodied energy and recycling potential.     

Comparative studies on protein fractions and amino acid composition from sorghum and pearl millet

A defatted flour sample of sorghum and pearl millet were separated into three fractions. These procedures involve extracting the defatted flour with aqueous sodium hydroxide (pH 11.9) followed by precipitation with diluted HCl acid (pH 4.8). The two protein fractions I (soluble at pH 4.8) and II (insoluble at pH 4.8) along with the remaining residues (fraction III) were lyophilized separately. The amino acid composition of the original flour and the three fractions were determined. Lysine seems to be the most deficient amino acid in the original flour and the remaining residues. Fraction I and II, in which the lysine accumulated, have essentially better amino acid profile and consequently nutritionally better quality than the protein of the original defatted flour. The recovered protein-rich fractions I and II should be useful as a protein ingredient in foods. The remaining residues can be extruded into convenience foods.