Solar adsorption refrigeration (SAR) system modeling

The solar adsorption refrigeration (SAR) system has economical and environmental aspects that motivate many researches to investigate its capability in cooling system design. In this study, multi-dimensional mathematical models have been generated to predict the coefficient of performance (COP) value of the SAR system as function of the evaporator, condenser, and generator temperatures. Fuzzy logic and regression analysis approaches were implemented to construct a mathematical model for this purpose from one-dimensional collected data that relates COP value separately to condensation, evaporation, and generation temperatures, respectively. The results of COP calculation from the two models were agreed quite well with the measured values. However, the fuzzy logic technique showed excellent accuracy than the regression model when compared to the calculated COP value, as its steps have the optimum nature in constructing the required model.     

Recent advances in modulated pulsed power magnetron sputtering for surface engineering

Over the past 10 years, the development of high-power pulsed magnetron sputtering (HPPMS) has shown considerable potential in improving the quality of sputtered films by generating a high degree of ionization of the sputtered species to achieve high plasma density by using pulsed, high peak target power for a short period of time. However, the early HPPMS technique showed a significantly decreased deposition rate as compared to traditional magnetron sputtering. Recently, an alternative HPPMS deposition technique known as modulated pulsed power (MPP) magnetron sputtering has been developed. This new sputtering technique is capable of producing a high ionization fraction of sputter target species and while at the same time achieving a high deposition rate. This paper is aimed at giving a review of recent advances in the MPP technique in terms of the plasma properties, the improvements in the structure and properties of the thin films, and the important advances in the high rate deposition of high quality thick coatings on the order of 20–100 μm in thickness.     

Rapid biological synthesis of silver nanoparticles using Kalopanax pictus plant extract and their antimicrobial activity

Silver nanoparticles (AgNPs) have promising potential in biomedicine, energy science, optics, and health care applications. We synthesized AgNPs using plant, Kalopanax pictus leaf extract. UV-visible spectrophotometric study showed the characteristic peak for AgNPs at wavelength 430 nm. The optical density at 430 nm increased after addition of plant leaf extract, indicating increase in formation of nanoparticles. Comparative time course analyses for AgNP synthesis carried out at different reaction temperatures (20, 60, and 90 °C) revealed higher reaction rate for K. pictus than Magnolia kobus plant leaf extract, which showed highest AgNP synthesis rate in the previous report. Electron microscopy analyses confirmed the presence of well dispersed AgNPs, predominantly with spherical shapes. In transmission electron microscopy, the particle size decreased with increase in temperature. Electron dispersive X-ray spectroscopy analyses indicated that Ag content increased with increase in reaction temperature. Fourier transform-infrared spectroscopy studies revealed capping of bioorganics from plant to the synthesized AgNPs. The antimicrobial activity of the synthesized AgNPs against Escherichia coli increased with increase in reaction temperature. The observations in this study will prove beneficial in approaching rapid synthesis of AgNPs and their antimicrobial application.     

Biofilm formation, cellulose production, and curli biosynthesis by Salmonella originating from produce, animal, and clinical sources

The ability of 71 strains of Salmonella enterica originating from produce, meat, or clinical sources to form biofilms was investigated. A crystal violet binding assay demonstrated no significant differences in biofilm formation by isolates from any source when tested in any of the following three media: Luria-Bertani broth supplemented with 2% glucose, tryptic soy broth (TSB), or 1/20th-strength TSB. Incubation was overnight at 30 degrees C under static conditions. Curli production and cellulose production were monitored by assessing morphotypes on Luria-Bertani agar without salt containing Congo red and by assessing fluorescence on Luria-Bertani agar containing calcofluor, respectively. One hundred percent of the clinical isolates exhibited curli biosynthesis, and 73% demonstrated cellulose production. All meat-related isolates formed curli, and 84% produced cellulose. A total of 80% of produce-related isolates produced curli, but only 52% produced cellulose. Crystal violet binding was not statistically different between isolates representing the three morphotypes when grown in TSB; however, significant differences were observed when strains were cultured in the two other media tested. These data demonstrate that the ability to form biofilms is not dependent on the source of the test isolate and suggest a relationship between crystal violet binding and morphotype, with curli- and cellulose-deficient isolates being least effective in biofilm formation.     

Improved Recovery Procedure for Evaluation of Sanitizer Efficacy in Disinfecting Contaminated Cantaloupes

ABSTRACT: Improved methodology for recovering microbial contaminants from cantaloupe surface is needed. Recovery of bacteria from the entire rind of cantaloupes, obtained with a mechanical peeler, and use of a new method for calculating melon surface area were investigated using melons inoculated with Salmonella Poona or Escherichia coli NRRL B-766. Growth of Salmonella but not E. coli was found during post-inoculation storage at 20°C. The new sampling methodology was equivalent to use of replicate rind plugs, taken at multiple sites on the melon surface, in recovery of both organisms. Recovery was the same by both procedures for dip- and spot-inoculated samples, sanitized or not sanitized, and for post-inoculation holding times up to 72 h. Survival of Salmonella on dip- and spot-inoculated cantaloupe surfaces following sanitizer wash treatments was similar. Keywords: cantaloupe, dip-inoculation, spot-inoculation, recovery, disinfection, microbiological safety     

Fourier‐based schemes with modified Green operator for computing the electrical response of heterogeneous media with accurate local fields

A modified Green operator is proposed as an improvement of Fourier‐based numerical schemes commonly used for computing the electrical or thermal response of heterogeneous media. Contrary to other methods, the number of iterations necessary to achieve convergence tends to a finite value when the contrast of properties between the phases becomes infinite. Furthermore, it is shown that the method produces much more accurate local fields inside highly conducting and quasi‐insulating phases, as well as in the vicinity of phase boundaries. These good properties stem from the discretization of Green's function, which is consistent with the pixel grid while retaining the local nature of the operator that acts on the polarization field. Finally, a fast implementation of the ‘direct scheme’ of Moulinec et al. (1994) that allows for parsimonious memory use is proposed. Copyright © 2014 John Wiley & Sons, Ltd.     

Estimation of key parameters in model for solute transport in rivers and streams

The exchange mechanisms associated with transient storage zones of a natural heterogeneous environment are often modified by unsteady water flux in the transient storage zone. This phenomenon can play an important role in the mass exchange between the free flowing water zone and the transient storage zones and may be the cause of the plateau region of the tail of observed concentration curves in natural streams. Deterministic interpretation methods are often used to generate the shape of the solute concentration curves in natural streams based on representations of transient storage exchange. Although many models are available to predict the parameters for the deterministic interpretation method, none can be used with confidence unless previously calibrated in the particular river reach under consideration. Therefore, the availability of reliable means for the provision of these parameters is usually the primary difficulty in the prediction of the rate of movement, dilution, and mixing of solute in rivers and streams. Measured tracer-response curves produced from the injection of a known quantity of soluble tracer provide one means for obtaining the requisite parameters. In this work, we advance an alternative approach based on the use of hydraulic and geometric information that are easily obtained in natural streams. Empirical equations used to predict the parameters are also analyzed to evaluate their behavior in representing solute mixing in natural streams with transient storage zones. Finally, the present proposals are validated against field meausrements of the solute concentration curves of chloride along a 1.2~km reach of the Shingobee River, Minnesota, U.S.A.     

Recovering recyclable materials from shredder residue

Each year, about 11 million tons of metals are recovered in the United States from about 10 million discarded automobiles. The recovered metals account for about 75 percent of the total weight of the discarded vehicles. The balance of the material, known as shredder residue, amounts to about three million tons annually and is currently landfilled. The residue contains a diversity of potentially recyclable materials, including polyurethane foams, iron oxides, and certain thermoplastics. This article discusses a process under development at Argonne National Laboratory to separate and recover the recyclable materials from this waste stream. The process consists essentially of two stages. First, a physical separation is used to recover the foams and the metal oxides, followed by a chemical process to extract certain thermoplastics. The status of the technology and the process economics are reviewed here.     

C3 and C4 plant species as energy sources and their potential impact on environment and climate

Careful selection of crop species, amoung other aspects, is very helpful in enhancing energy production by way of increased biomass yields from agricultural land. A wide range of C₃ and C₄ plant species has been introduced and investigated for their environmental and climatic impact. The results indicate already that some perennial C₄ crop species posses high yield potential, lower erosion-index, better CO₂ reduction rates and need less fertilizer, water and chemicals.     

Comparison of thermal comfort algorithms in naturally ventilated office buildings

With the actual environmental issues of energy savings in buildings, there are more efforts to prevent any increase in energy use associated with installing air-conditioning systems. The actual standard of thermal comfort in buildings ISO 7730 is based on static model that is acceptable in air-conditioned buildings, but unreliable for the case of naturally ventilated buildings. The different field studies have shown that occupants of naturally ventilated buildings accept and prefer a significantly wider range of temperatures compared to occupants of air-conditioned buildings. The results of these field studies have contributed to develop the adaptive approach. Adaptive comfort algorithms have been integrated in EN15251 and ASHRAE standards to take into account the adaptive approach in naturally ventilated buildings. These adaptive algorithms seem to be more efficient for naturally ventilated buildings, but need to be assessed in field studies. This paper evaluates different algorithms from both static and adaptive approach in naturally ventilated buildings across a field survey that has been conducted in France in five naturally ventilated office buildings. The paper presents the methodology guidelines, and the thermal comfort algorithms considered. The results of application of different algorithms are provided with a comparative analysis to assess the applied algorithms.