Modeling and simulation of solar pond floor heating system

This paper presents the development of modeling, simulation and analysis of a solar pond floor heating system. The developed computer simulation has been used to study the potential of using such a system under climatic conditions in Jordan. It was found that the solar pond heating system could meet most of the winter season in Jordan with Solar fraction in the range 80–100% for at least 2 months of the season. It must be emphasized that the feasibility of such a system is its utilization in district heating and not for individual households due to the limiting economical factors of high capital cost of the solar pond for small domestic applications.     

Superstructure-based design and operation for biomass utilization networks

This paper is providing a design and evaluation methodology for biomass utilization networks (B-NETs) planning in local areas. The methodology is an effort to integrate various exertions of many researchers as well as stakeholders in the biomass field including process technologies, local area classification and renewable energy mechanisms to design and evaluate B-NETs. The proposed design methodology has three steps: classification, problem formulation and suggesting solution methods. The core part of planning the B-NETs utilization methodology is the superstructure that is a super class model for the processes of biomass utilization networks that has to be built for the local area. The biomass utilization superstructure (BUSS) relates the biomass resources to their products, available processes, and possible future processes of utilization in static manner. Although the local area BUSS is static in nature, it shows the decision makers what kinds of B-NETs are, or can be, available in their area. It is important to note that for each super class process there exists a number of elemental technologies, or what we call unit process (UP), that can perform the job under the same condition with different processing constraint. To support the design and operation process a technological information infrastructure (TII) needs to be built to work as an information pool and simulation tool. With the support of TII and the BUSS different scenarios can be synthesized, analyzed and compared. Scenarios development enables the designer to check processing alternatives as well as biomass promotion mechanisms that fit the concerns of various stakeholders. The results of the methodology application can be given in the form of suggestions of a specific network class(es) or scenarios that can be applied in a class of localities with the same characteristics. Following to methodology configuration, a proposal for optimization methods is discussed and a case study for comparing biomass network scenarios in mountainous city is introduced.     

Temperature dependence of the IR-absorbances of diphenylcarbinol

The temperature dependence of the absorbances of IR-absorption bands corresponding to the fundamental, overtones and combination frequences of diphenylcarbinol in the pure liquid phase is presented. The range of temperature taken in this investigation is between 68 and 298°C. Many difficulties have been met with in trying to find a relation connecting the symmetry of the vibrations and the temperature effect on their absorbances. As shown, in the text, the change in the absorbances of the bands and the temperature variation is linear even for the broad bands.     

Microscopic image analysis for quantitative measurement and featureidentification of normal and cancerous colonic mucosa

The development of an automated algorithm for the categorization of normal and cancerous colon mucosa is reported. Six features based on texture analysis were studied. They were derived using the co-occurrence matrix and were angular second moment, entropy, contrast, inverse difference moment, dissimilarity, and correlation. Optical density was also studied. Forty-four normal images and 58 cancerous images from sections of the colon were analyzed. These two groups were split equally into two subgroups: one set was used for supervised training and the other to test the classification algorithm. A stepwise selection procedure showed that correlation and entropy were the features that discriminated most strongly between normal and cancerous tissue (P<0.0001). A parametric linear-discriminate function was used to determine the classification rule. For the training set, a sensitivity and specificity of 93.1% and 81.8%, respectively, were achieved, with an overall accuracy of 88.2%. These results mere confirmed with the test set, with a sensitivity and specificity of 93.1% and 86.4%, respectively, and an overall accuracy of 90.2%     

MODELING OF ETHANOL BIOPRODUCTION IN THREE-PHASE FLUIDIZED BED REACTORS

A time dependent and one-dimensional model is developed to analyze the performance of three-phase fluidized reactors and is applied to the fermentation of glucose to ethanol. The reactor model takes into consideration the presence of three different phases; the yeast (solid) which is continuously fluidized by the liquid stream, the gas bubbles which greatly enhance mixing and the wake phase which follows the tracks of the gas bubbles. The reactor performance is analyzed as a function of major operating conditions. The analysis includes variations in dispersion of glucose and yeast inside the reactor, the concentration of glucose in feed, and of the yeast mass inside the reactor, reaction temperature, velocities of gas and liquid feeds, and reactor aspect ratio. Computed glucose conversion is presented as a function of reactor length and time. The results indicate that high glucose conversions can be obtained at high gas velocities, low liquid flow rates, large aspect ratios, high yeast concentration, and an optimum operating temperature of 36°C,     

Trypanosoma cruzi: effect of immunization on the risk of vector-delivered infection in guinea pigs

The protective effect of experimental immunization was studied in guinea pigs exposed to vectorial infection by Trypanosoma cruzi. Immunized animals received an inoculum of live-attenuated T. cruzi epimastigotes into a granuloma previously induced by Freund's complete adjuvant in the hind footpad. Seven days later, a delayed-type hypersensitivity reaction was triggered by reinjection of the parasites in the front footpad. The animals were then placed in Triatoma infestans-colonized corrals and exposed to vectorial T. cruzi transmission of the parasite for up to 200 days. The effectiveness of this immunizing protocol was controlled in terms of the number of bites necessary for infection (NBNI) in immunized as compared with control animals. Periodic entomological census allowed for the determination of vector biting and infection rates and the calculation of NBNI. Although this measurement was quite variable between yards, an overall average of 4,973 bites was enough to infect a control guinea pig in 4 separate experiments. The corresponding figure for the experimental group was 21,307 bites, implying that immunized animals could resist a 4.28-fold increase (range: 1.99-8.32) in the number of vector bites before becoming infected.     

Fe2O3/TUD-1: an efficient catalysts for Friedel–Crafts alkylation of aromatics

Three-dimensional mesoporous (Fe-TUD-1) catalysts with different Si/Fe ratios (100, 50, 20 and 10) are prepared using triethanolamine as template. Physicochemical and textural measurements by XRD, elemental analysis, N₂ adsorption, UV–Vis spectroscopy and HR-TEM imaging indicate the formation of pure solid mesoporous materials and the presence of Fe₂O₃ nanoparticles in the prepared Fe-TUD-1 samples. The catalytic performance of Fe-TUD-1 catalysts is tested in Friedel–Crafts alkylations of single-ring aromatic compounds [e.g. toluene (T), ethyl benzene (EB) and cumene (C)] by benzyl alcohol (BnOH). Dispersion of Fe(III) in the mesoporous matrix of TUD-1 enhanced the catalytic activity of Fe-TUD-1 in the alkylation of aromatic compounds compared to pure Fe₂O₃ and TUD-1 catalysts. The catalytic activity further increases by the decreasing of Si/Fe ratio. Sample loaded with Si/Fe ratio = 10 (Fe-10) showed almost complete conversion of BnOH in a relatively very short reaction time (<30 min) with 95 % selectivity. The catalytic performance of Fe-TUD-1 was superior to other metal-containing TUD-1 (e.g. Ga, Sn, and Ti) catalysts, or other Fe-containing catalysts (e.g. Fe-MCM-41, ZSM-5 and Fe-HMS). Alkylation of C is the fastest among the three aromatic substrates investigated (at temperatures very close to their boiling points) due to the largest inductive effect by the isopropyl group compared to the methyl group of T and the ethyl group in EB. Dibenzyl ether is formed as a byproduct only in the early times of the reaction and proved to act as alkylating agent after being hydrolyzed backwards to reform BnOH. Leaching experiments show the Fe-TUD-1 materials are very stable and can be reused as alkylation catalyst.     

Cobalt/copper-decorated carbon nanofibers as novel non-precious electrocatalyst for methanol electrooxidation

In this study, Co/Cu-decorated carbon nanofibers are introduced as novel electrocatalyst for methanol oxidation. The introduced nanofibers have been prepared based on graphitization of poly(vinyl alcohol) which has high carbon content compared to many polymer precursors for carbon nanofiber synthesis. Typically, calcination in argon atmosphere of electrospun nanofibers composed of cobalt acetate tetrahydrate, copper acetate monohydrate, and poly(vinyl alcohol) leads to form carbon nanofibers decorated by CoCu nanoparticles. The graphitization of the poly(vinyl alcohol) has been enhanced due to presence of cobalt which acts as effective catalyst. The physicochemical characterization affirmed that the metallic nanoparticles are sheathed by thin crystalline graphite layer. Investigation of the electrocatalytic activity of the introduced nanofibers toward methanol oxidation indicates good performance, as the corresponding onset potential was small compared to many reported materials; 310 mV (vs. Ag/AgCl electrode) and a current density of 12 mA/cm² was obtained. Moreover, due to the graphite shield, good stability was observed. Overall, the introduced study opens new avenue for cheap and stable transition metals-based nanostructures as non-precious catalysts for fuel cell applications.     

Hierarchical TiO2/ZnO Nanostructure as Novel Non-precious Electrocatalyst for Ethanol Electrooxidation

Metal oxides have a higher chemical stability in comparison to metals,so they can be utilized as electrocatalysts if the activity could be enhanced.Besides the composition,the morphology of the nanostructures has a considerable impact on the electrocatalytic activity.In this work,zinc oxide nano branches-attached titanium dioxide nanofibers were investigated as an economic and stable catalyst for ethanol electrooxidation in the alkaline media.The introduced material has been synthesized by electrospinning process followed by hydrothermal technique.Briefly,electrospinning of colloidal solution consisting of titanium isopropoxide,poly(vinyl acetate) and zinc nanoparticles was performed to produce nanofibers embedding solid nanoparticles.In order to produce TiO_2 nanofibers containing ZnO nanoparticles,the obtained electrospun nanofiber mats were calcined in air at 600 °C.The formed ZnO nanoparticles were exploited as seeds to outgrow ZnO branches around the TiO_2 nanofibers using the hydrothermal technique at sub-critical water conditions in the presence of zinc nitrate and bis-hexamethylene triamine.The morphology of the final product,as well as the electrochemical measurements indicated that zinc nanoparticles content in the original electrospun nanofibers has a significant influence on the electrocatalytic activity as the best performance was observed with the nanofibers synthesized from electrospun solution containing 0.1 g Zn,and the corresponding current density was 37 mA/cm~2.Overall,this study paves a way to titanium dioxide to be exploited to synthesize effective and stable metal oxide-based electrocatalysts.