Assessment of a regulatory sanitization process in Egyptian dairy plants in regard to the adherence of some food-borne pathogens and their biofilms

Food-borne pathogens may develop certain strategies that enable them to defy harsh conditions such as chemical sanitization. Biofilm formation represents a prominent one among those adopted strategies, by which food-borne pathogens protect themselves against external threats. Thus, bacterial biofilm is considered as a major hazard for safe food production. This study was designed to investigate the adherence and the biofilm formation ability of some food-borne pathogens on stainless steel and polypropylene surfaces using chip assay, and to validate regular sanitizing process (sodium hypochlorite 250mg/L) for effective elimination of those pathogens. Sixteen pathogenic bacterial strains, previously isolated from raw milk and dairy products at Zagazig city, Egypt (9 Staphylococcus aureus, 4 Cronobacter sakazakii and 3 Salmonella enterica serovar Typhimurium), were chosen for this study. Strains showed different patterns of adherence and biofilm formation on tested surfaces with minor significance between surfaces. The ability of sodium hypochlorite to completely eradicate either adhered or biofilm-embedded pathogens varied significantly depending on the strain and type of surface used. Whilst, sodium hypochlorite reduced tested pathogens counts per cm(2) of produced biofilms, but it was not able to entirely eliminate neither them nor adherent Cronobacter sakazakii to stainless steel surface. This study revealed that biofilm is considered as a sustainable source of contamination of dairy products with these pathogens, and also emphasized the need of paying more attention to the cleaning and sanitizing processes of food contact surfaces.     

Citric acid used as a crosslinking agent for the grafting of chitosan onto woolen fabric

Modification of woolen fabrics was done by the grafting of low‐molecular‐weight deacetylated chitosan in the presence of citric acid as a crosslinking agent with the pad–dry cure method at different conditions (times and temperatures). The add‐on of chitosan and the optimum conditions were determined. The improved properties of modified wool by chitosan were evaluated with the urea bisulfite solubility test, crease recovery angle, yellowness index, and scanning electron microscopy. The dyeing properties of modified wool fabrics were studied with acid and reactive dyes. The biocidal activities of the modified and unmodified wool samples were evaluated and compared against some species of microorganisms, including Escherichia coli (Gram negative), Staphylococcus aureus (Gram positive), Candida albicans, and Aspergillus flavus. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

A Flooded Thirsty World

New stories and images are necessary to bolster an ethical inquiry of climate change and mobilize climate action. But what form should such stories take? In this essay, I argue that speculative fiction can make public the climate crisis, not only as a calamity of the physical environment but also as a predicament of the cultural environment—of the systems of representation through which society has related to complex environmental issues among their various actors and in the vast scales of time and space. The essay amplifies the environmental uncanny to produce a speculative fiction that grapples with something as indescribable as climate change. In conclusion, “Of Oil and Ice,” a geostory, casts an iceberg as a planetary protagonist and relates its trajectory as it migrates from the Antarctic ice shelf to a glass of water in the Persian Gulf.     

Potential of using nonwoven polyester fabric (NWPF) as a packing media in multistage passively aerated biological filter for municipal wastewater treatment

The performance of a multistage passively aerated biological filter (PABF) packed with Nonwoven polyester fabric (NWPF) for municipal wastewater treatment was investigated under different operating conditions. The system was operated at different hydraulic retention times (HRTs) of 2.3, 1.72 and 1.38 h and corresponding to organic loading rates (OLRs) of 1.77, 2.15 and 2.9 kg BOD/m³. d. Increasing HRT and decreasing OLR, increased dissolved oxygen (DO) and consequently increased the removal rate of organic matters (87%), suspended solids (95.8%) and ammonia (88%). Profile results from different compartments showed that the major part of organic and suspended matters was removed in the upper layers of the system, whereas most of the suspended solids were trapped, while the nitrification process took place in the lower part of the PABF system because of the increase in DO concentrations. The results proved the advantage of using NWPF. It has pleated and rough surface which retain more biomass compared with plain surface. Excess biomass produced from PABF was negligible compared to conventional treatment systems.     

Applying design science approach to architectural design development

Unlike research methods for social and positivist sciences, those for architectural design lack a discipline-specific conceptual framework. Performative science aims at producing outcomes for future use and therefore needs a robust methodological approach that encompasses different techniques and methods supporting an evidence-based architectural design development. This study suggests that design science can be successfully applied to architectural design development and provides architects and designers with a powerful tool bridging the gap between research and design. In so doing, this study explores the application of design science to implement a user-centered design approach. A design challenge is reframed within the robust framework of design science by referring to a case study on refugee shelters. The traditional method by which shelter optimization is pursued by designers is questioned by involving the final users through an ethnographic approach within the framework of design science. The design outcome produced through this process is a list of specifications allowing designers to create different architectural solutions and matching the requirements expressed by future users. The authors argue that a user-centered design outcome can be achieved and validated through design science.     

Optimal reactive power dispatch using ant colony optimization algorithm

This paper proposed a procedure to solve the optimal reactive power dispatch (ORPD) problem using ant colony optimization (ACO) algorithm. The objective of the ORPD problem is to minimize the transmission power losses under control and dependent variable constraints. Proposed sensitivity parameters of reactive power at generation and switchable sources are derived based on a modified model of fast decoupled power flow. The proposed ACO-based algorithm is applied to the IEEE standard 14-bus, 30-bus systems, and a real power system at West Delta Network as a part of the Unified Egyptian Network. The obtained simulation results are compared with those of conventional linear programming, genetic algorithm, and particle swarm optimization technique. Simulation results show the capability of the proposed ACO-based algorithm for solving the ORPD problem, especially with increasing the system size.     

Facile synthesis of hybrid nanocomposite based on chitosan binary metal oxides for high-performance supercapacitor

The advancement in materials for energy storage for supercapacitors has been supported by the current shortage of energy as well as the increasing availability of sources of clean energy. Consequently, two-dimensional materials based on metal oxide nanoparticles (copper oxide (CuO) and zinc oxide (ZnO), have great potential for the previously discussed utilization. A simple and affordable solid-state approach was employed to design hybrid nanocomposite based on chitosan (Cs) blended with ZnO and CuO; this nanocomposite was labeled with CZC. The structural, morphological investigation of CZC hybrid nanocomposites, and X-ray diffraction (XRD) of the prepared nanocomposites were characterized. Consequently, hybrid nanocomposites for application as electrodes for supercapacitor devices were developed. The hybrid nanocomposite (CZC-3) shows improved cycle stability, high energy density, and a specific capacitance in the electrochemical activity. Remaining at 97.8% of the initial capacitance even after 5000 cycles. These results imply that the hybrid nanocomposite based on Cs/ZnO/CuO has a promising future as a supercapacitor electrode material. Additionally, it provides superior performance to other nanocomposites with a high specific capacitance of 638.3 F/g and about 86.98% capacity retention after 5000 cycles at a current density of 1 A/g.     

Citric Acid Used as a Cross-Linking Agent for Grafting β-Cyclodextrin onto Wool Fabric

Modification of woolen fabrics were achieved by grafting β-cyclodextrin and β-chloro triazinylcyclodextrin in the presence of citric acid (CA) as cross-linking agent and phosphorous salts such as sodium hypophosphite (SHP) and sodium dihydrogen phosphate (SDP) using the pad dry cure technique. CA is expected to react with the β-CD (or wool) hydroxyl groups and wool terminal amino groups, to form ester cross-linkages or ionic bonds. The improved properties of wool fabrics were evaluated using urea bisulfite solubility test, tensile strength, elongation and crease recovery angle. Also, yellowness index and scanning electron microscopy were performed. Woolen fabrics treated with CA alone and CA/ CD shows antimicrobial properties.     

High temperature tribological behaviour of carbon based (B4C and DLC) coatings in sliding contact with aluminum

Carbon based coatings, particularly diamond-like carbon (DLC) films are known to resist aluminum adhesion and reduce friction at room temperature. This attractive tribological behaviour is useful for applications such as tool coatings used for aluminum forming and machining. However, for those operations that are performed at elevated temperatures (e.g. hot forming) or that generate frictional heat during contact (e.g. dry machining) the suitable coatings are required to maintain their tribological properties at high temperatures. Candidates for these demanding applications include boron carbide (B₄C) and DLC coatings. An understanding of the mechanisms of friction, wear and adhesion of carbon based coatings against aluminum alloys at high temperatures will help in designing coatings with improved high temperature tribological properties. With this goal in mind, this study focused on B₄C and a hydrogenated DLC coatings sliding against a 319 grade cast aluminum alloy by performing pin-on-disk experiments at temperatures up to 400 °C. Experimental results have shown that the 319 Al/B₄C tribosystem generated coefficient of friction (COF) values ranging between 0.42 and 0.65, in this temperature range. However, increased amounts of aluminum adhesion were detected in the B₄C wear tracks at elevated temperatures. Focused ion beam (FIB) milled cross sections of the wear tracks revealed that the coating failed due to shearing along the columnar grain boundaries of the coating. The 319 Al/DLC tribosystem maintained a low COF (0.15-0.06) from room temperature up to 200 °C. This was followed by an abrupt increase to 0.6 at 400 °C. The deterioration of friction behaviour at T > 200 °C was attributed to the exhaustion of hydrogen and hydroxyl passivants on the carbon transfer layer formed on the Al pin.