Drying of Wheat Based on the Non-Equilibrium Thermodynamics: A Numerical Study

A new mathematical model to describe simultaneous heat and mass (liquid and vapor) transfer and shrinkage during drying of capillary-porous bodies with particular reference to prolate spheroid solid is presented. As an application, the methodology was used to predict drying of soft red winter wheat (Arthur). The mathematical model was based on the nonequilibrium thermodynamics considering variable transport coefficients and convective boundary conditions at the surface of the solid. All the partial differential equations presented in the model have been written in prolate spheroidal coordinates and solved numerically by a finite-volume method using implicit fully formulation. Results of the drying and heating kinetics and moisture content and temperature distributions in a wheat kernel during drying process are presented and analyzed. The methodology allows verification of the heat, liquid, and vapor fluxes, taking into account the thermal and hydrical gradients inside the grain.     

Transport of Dissolved Si from Soil to River: A Conceptual Mechanistic Model

This paper reviews the processes which determine the concentrations of dissolved silicon (DSi) in soil water and proposes a conceptual mechanistic model for understanding the transport of Si through soils to rivers. The net DSi present in natural waters originates from the dissolution of mineral and amorphous Si sources in the soil, as well as precipitation processes. Important controlling factors are soil composition (mineralogy and saturated porosity) and soil water chemistry (pH, concentrations of organic acids, CO₂ and electrolytes). Together with production, polymerization and adsorption equations they constitute a mechanistic framework determining DSi concentrations. We discuss how key controls differ across soil horizons and how this can influence the DSi transport. A typical podzol soil profile in a temperate climate is used as an example, but the proposed model is transferrable to other soil types. Additionally, the impact of external forcing factors such as seasonal climatic variations and land use is evaluated. This blueprint for an integrated model is a first step to mechanistic modelling of Si transport processes in soils. Future implementation with numerical methods should validate the model with field measurements.     

Cold Plasma Modification Effects on the Water Flow through Sintered UHMWPE Membranes

Natural rubber latex and various concentration of natural antioxidant were blended in different ratios and irradiated at various absorbed doses by gamma rays from Co-60 source at room temperature. The aqueous extraction of Diospyros peregrina was used as natural antioxidant. It was found that the addition of different concentration of natural antioxidant into natural rubber latex improve the aging property of the film. Decreasing in tensile strength of rubber film with 10 phr natural antioxidant and 15 kGy radiation dose after 24 hours aging at 100°C was 9.34% compared to 13.89% for film without natural antioxidant. The tensile strength, tear resistance and modulus at 500% elongation of the rubber film were found to be optimum at 15 kGy radiation dose and with 10 phr natural antioxidant. Elongation at break, permanent set and swelling ratio decreases with the increasing absorbed radiation dose as well as the concentration of the natural antioxidant.     

CORRELATION AND PREDICTION OF VLE OF WATER + CONGENER MIXTURES FOUND IN ALCOHOLIC BEVERAGES USING AN ARTIFICIAL NEURAL NETWORK

Artificial neural networks have been used for the correlation and prediction of vapor-liquid equilibrium data of binary water mixtures found in alcoholic beverage production. The main interest of the study is the accurate modeling of the bubble pressure and concentration of congeners in the vapor phase (substances different from ethanol and water), considered to be an important enological parameter in the alcoholic industry. Nine binary water + congener mixtures were considered for analysis. Vapor-liquid equilibrium data of these systems were taken from the literature (333 data points for training and 111 data points for testing), the artificial neural network results were compared with available literature data, and the accuracy of the modeling is discussed. The study shows that the neural network model is a good alternative method for the estimation of phase equilibrium properties for this type of mixture.

Supplemental materials are available for this article. Go to the publisher's online edition of Chemical Engineering Communications to view the free supplemental file. http://www.informaworld.com/smpp/title~db=all~content=t713454788     

CRITICAL FLUX DETERMINATION IN ULTRAFILTRATION OF WASTEWATER FROM A FOOD INDUSTRY BY OPTIMIZATION METHOD

Two ultrafiltration membranes with different geometries (spiral polymeric and tubular ceramic) but similar cutoffs were used to treat wastewater from a food industry. Hydrodynamic conditions were optimized by statistical methods as a strategy to get more accurate values of the critical parameters and then to produce higher water flux and minimization of membrane fouling. The validation of the optimization method was obtained by experimental critical flux determination at critical parameters. Membrane fluxes revealed significant differences during filtration. The polymeric membrane showed an optimal flux of 45.60 Lh^?1 m^?2 at 3.21 bar while operating at a stable time of 11.61 h, whereas optimal flux of the ceramic membrane was 32.43 Lh^?1 m^?2 at 3.98 bar for 16.03 h. Experimental critical flux values were only slightly lower than optimal fluxes for both membranes, showing the validity of the statistics models applied. Negligible osmotic pressure was found on the two membranes at critical flux parameters, indicating irreversible fouling for both cases. The polymeric membrane revealed strong fouling behavior and the ceramic membrane showed a weak form; the flux decline occurred first in the polymeric membrane, whereas the ceramic membrane exhibited high stability during the filtration operations. A high degree of purification of wastewater was obtained by this membrane at critical flux conditions.     

Fungal fucoidanase production by solid-state fermentation in a rotating drum bioreactor using algal biomass as substrate

Fucoidanase enzymes able to degrade fucoidan were produced by solid-state fermentation (SSF). The fermentation assays were initially carried out in a laboratory-scale rotating drum bioreactor, and two fungal strains (Aspergillus niger PSH and Mucor sp. 3P) and three algal substrates (untreated, autohydrolyzed, and microwave processed seaweed Fucus vesiculosus) were evaluated. Additionally, fermentations were carried out under rotational (10 rpm) and static conditions in order to determine the effect of the agitation on the enzyme production. Agitated experiments showed advantages in the induction of the enzyme when compared to the static ones. The conditions that promoted the maximum fucoidanase activity (3.82 U L^?1) consisted in using Mucor sp. 3P as fungal strain, autohydrolyzed alga as substrate, and the rotational system. Such conditions were subsequently used in a 10 times larger scale rotating drum bioreactor. In this step, the effect of controlling the substrate moisture during the enzyme production by SSF was investigated. Moreover, assays combining the algal substrate with an inert support (synthetic fiber) were also carried out. Fermentation of the autohydrolyzed alga with the moisture content maintained at 80% during the fermentation with Mucor sp. 3P gave the highest enzyme activity (9.62 U L^?1).     

Synthesis and characterization of mesoporous anatase TiO2 nanostructures via organic acid precursor process for dye-sensitized solar cells applications

Titania (TiO₂) nanoparticles have been synthesized using organic precursor technique. The titania nanoparticles were characterized. The results indicated that the prepared titanium oxalate and citrate precursors were transformed to anatase TiO₂ phase at temperature 400 °C for 2 h. Dye-sensitized solar cells were assembled using the prepared nanocrystalline TiO₂ with large surface area. The specific surface area S_BET was 80.9 and 78.6 m²/g using oxalic and citric acids, respectively. The power efficiency was 3.5 and 2.4%. A brief discussion on the possible reasons behind the low power conversion efficiency observed for these type of solar cells was reported.     

Viability of a native isolate of Lactobacillus brevis in a fermented milky drink

The objective of this research was to test the viability of a native isolate of Lactobacillus brevis in two fermented milky drinks: a drink without prebiotic ingredient and another drink with oat flour (0.5%, p/v) as prebiotic ingredient. The viability of L. brevis was tested at 7, 14, and 21 after inoculation. Drink pH and lactic acid concentration was measured as a function of time (2, 7, 14, and 21 days after inoculation). The isolate was viable in both drinks because its counting plates was higher than 10(6) CFU/mL until day 21st. Between the 7th and 14th day, the rate of growth was higher in the drink that included oat flour, however, at the day 21st the colony density was similar in both drinks.     

Bioactive peptides derived from milk proteins

Milk proteins are known for having a wide range of nutritional, functional and biological properties that make them important ingredients in functional or health promoting foods. These properties are partly attributed to bioactive peptides coded in the different milk proteins. Bioactive peptides are inactive within the protein sequence but may be released by the action of native proteolitic enzymes from milk, enzymes from lactic acid bacteria or from exogenous sources or may be produced during gastrointestinal digestion or processing of foods. Peptides derived from caseins and whey proteins were shown to present several bioactive properties such as opioid, antihypertensive, antimicrobial, immunodulatory, mineral carrier and antithrombotic. This overview presents a perspective of the importance of dairy proteins in the production of bioactive peptides and their biological activities, as well as the main analytical tecniques that have been used for the isolation and identification of these peptides.     

Performance of fluorine-added CoMoS/Al2O3 prepared by sonochemical and chemical vapor deposition methods in the hydrodesulfurization of dibenzothiophene and 4,6-dimethyldibenzothiophene

The performance of a new type of CoMoS/Al₂O₃ catalyst, with added fluorine and prepared by sonochemical and chemical vapor deposition (CVD) methods, was investigated in the hydrodesulfurization (HDS) of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). The catalyst, which was designed to contain optimum amounts of fluorine and cobalt, exhibited a higher activity, ca. 4.6 times higher activity particularly in the HDS of 4,6-DMDBT, than a fluorine-free catalyst prepared by a conventional impregnation method. The enhanced activity of the new catalyst can be attributed to the cumulative effects of individual factors involved in the catalyst preparation. That is, the use of a sonochemical synthesis led to a high dispersion of small MoS₂ crystallites on the alumina, and the addition of the Co species to the catalyst by CVD caused a close interaction between the Co species and the MoS₂ crystallites to produce numerous CoMoS species, which are the catalytically active species for HDS. The addition of fluorine increased the amounts of acidic sites in the catalyst, which promoted hydrogenation (HYD) route to a greater extent than the direct desulfurization (DDS) route in DBT HDS and both HYD and DDS routes to similar extents in the case of 4,6-DMDBT HDS. Accordingly, the addition of fluorine led to a greater increase in catalytic activity for 4,6-DMDBT HDS than for DBT HDS.