Antibacterial effects of chitosan coating containing Mentha aquatica L. essence against Escherichia coli,Staphylococcus aureus and Listeria monocytogenes in Iranian white cheese

The effect of a chitosan coating and Mentha aquatica L. essence on Iranian white cheese was investigated. Results showed 100% inhibition of Escherichia coli growth using 1.5% essence after 10 days. After 15 days of incubation, the Staphylococcus aureus population was reduced by 44.2%, 70.0%, and 88.5% using 0.5, 1.0 and 1.5% essence, respectively. After 15 days, Listeria monocytogenes growth was inhibited by 63.84%, 70.12%, and 85.9% using 0.5, 1.0, and 1.5% essence, respectively. Inhibition zone diameter studies also confirmed the antibacterial effects of applied coating against all the above‐mentioned bacteria in Iranian white cheese.     

Feasibility of Ni/Ti and Ni/GF cathodes in microbial electrolysis cells for hydrogen production from fermentation effluent: A step toward real application

The low cost, low over-potential loss, good catalytic properties for hydrogen evolution reaction (HER), high corrosion stability, commercially available, and could be applied in pH-neutral solution and ambient temperature are important properties for the cathode materials when it is applied in microbial electrolysis cell (MEC) technology. This study has two-pronged objectives: the first is to investigate the feasibility of titanium (Ti) and graphite felt (GF) coated with nickel (Ni), and the second is to generate hydrogen from the fermentation effluent (FE). The electrodeposition (ED) method was used to deposit Ni catalyst onto Ti (Ni/Ti) and GF (Ni/GF) surfaces. The scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy were used to characterize the cathode morphology and element composition. The catalytic properties of Ni/Ti and Ni/GF could be evaluated using the linear sweep voltammetry tests. The maximum volumetric H₂ production rates of MEC using Ni/Ti and Ni/GF cathodes were obtained at 0.39 ± 0.01 and 0.33 ± 0.03 m³ H₂ m⁻³ d⁻¹ respectively. The Ni/Ti and Ni/GF cathodes could be used as alternative cathodes while producing hydrogen from FE.     

Double Dianhydride Backbone Polyimide Aerogels with Enhanced Thermal Insulation for High‐Temperature Applications

Aerogels owe their high thermal insulation and other unique properties to their nanostructure configuration. However, controlling the aerogels' morphology is always a scientific challenge. In this study, double dianhydride backbone (double backbone) polyimide aerogels with tailored nanostructure assembly are created for the first time. This is achieved by controlled polymerization reaction of oligomers with distinct dianhydride monomers. Combining the two oligomers through a controlled polymerization reaction is a successful strategy for tailoring the aerogels nanostructure assembly as well as other properties. The fabricated double backbone aerogel presents 40% reduced thermal conductivity of 19.7 mW mK^?1 over previously studied polyimide aerogels along with the compression modulus of 1.64 MPa at a relatively low density of 0.068 g cm^?3. Such low thermal conductivity is comparable with the inorganic counterparts. Light in weight and high thermally insulated polyimide aerogels with suitable mechanical properties and high service temperature are an appropriate replacement for current fireproof insulation materials.     

An analysis of construction productivity differences between Canada and the United States

Comparisons of industry sectors in advanced economies since the 1960s show that the construction sector has lagged in productivity growth rates, especially in the United States. Although the US and Canadian economies are highly integrated, Canada’s experience differs in key ways. Analysis of these differences offers insight into fundamental construction productivity drivers. Three levels of analyses of construction productivity in the US are provided in this study. The first analysis compared international levels of labour productivity growth. The second compared construction productivity between the US and Canada, and the third analysed cost estimating data from RS Means estimating manuals to measure the changes in labour and partial factor productivity in the US from 1995 to 2009. Statistical significance testing indicates that labour productivity remained nearly constant in the building sub-sector and that partial factor productivity has improved at an annual compound rate of 0.66%. This supports previous findings that US construction has stagnated but is still improving in Canada, with wage differentials and training systems as potential drivers of this difference. While growth rates of productivity seem to decline with higher absolute levels of productivity, there is no evidence that high absolute productivity levels preclude significant growth.     

Fatigue Crack Tip Plasticity for Inclined Cracks

The evaluation of the crack tip deformation is essential to the estimation of crack growth under either static or cyclic loading. A 3-D elastic–plastic finite element analysis was developed to simulate the crack tip deformation along mixed mode inclined edge cracks in a steel plate subjected to either monotonic or cyclic loading at selected R-ratios. In this paper, two types of crack configurations were investigated: inclined cracks with equal inclined lengths (EICL) and inclined cracks with equal horizontal projection length (ECHP). The development of the monotonic (Δm) and cyclic (Δc) crack tip plastically zones and the monotonic (CTOD) and cyclic (ΔCTOD) crack tip opening displacements were traced to find the effect of the crack inclination angle, which significantly affected the size and shape of the crack tip plastic zone. The finite element results compared well with the analytical results based on modified Dugdale’s model. It was observed that Mode II has a significant effect on the plastic zone in the case of equal inclined crack length (EICL), i.e., Mode II increases as the crack angle decreases. Also, it is interesting to note that for the EICL case, the magnitude of Δc is delayed to appear with decreasing the inclination angle, for example, for θ?=?90° the cyclic plastic zone appeared at Δσ?=?103.32 MPa, while for θ?=?45° the cyclic plastic zone appeared at Δσ?=?132.84 MPa. Whereas, the variation of monotonic and cyclic plastic zone size in the equal crack horizontal projection (ECHP) case is not affected by the crack inclination angle. Furthermore, it was observed that the static crack tip opening displacement (CTOD) and the cyclic (ΔCTOD) are independent of the crack inclination angle in case of ECHP, due to such cracks take into consideration the effect of inclination angle through its length.     

Microbial fuel cell-based sensor for Enterobacter sp. KBH6958 activity monitoring during hydrogen production: the effects of pH and glucose concentration

Journal of Applied Electrochemistry - A microbial fuel cell (MFC) is an electricity-generating device utilising electrochemically active microorganisms as biocatalysts. Using MFC as a biosensor to...     

Small/medium nuclear reactors for potential desalination applications : Mini review

Small/medium nuclear reactors (SMRs) are a promising alternative for powering large scale desalination plants. The modern generations of these systems manifest cost effectiveness and built-in safety features. The compatibility with geological and topological challenges is an added advantage. Moreover, funding opportunities and packages could be easily arranged for small/medium nuclear reactors (SMR). This mini review article provides the latest technical features of SMR nuclear plants with emphasis on pressurized light water reactors (PWR), boiling water reactors (BWR), heavy water reactors (HWR), gas cooled reactors (GCR), and liquid metal fast breeder reactors (LMFBR). Preliminary cost indicators for typical units were investigated as a part of joint effort to develop a cost database for these types of reactors. Security and safety features of small/medium reactors are identified and reviewed. This paper identifies and briefly discusses the various types of small/medium nuclear reactors to provide a preliminary evaluation and consideration of using this type of reactor in potential seawater desalination applications.     

Online droplet diameter measurements to improve the crude oil dehydration process

Emulsion droplet size is information of paramount importance in the design and evaluation of oil–water separators. This paper describes the application of a technique for in situ determination of water droplet diameter distribution (DDD) in actual production scenarios. We discuss the DDD and water content measurements in emulsions obtained during normal operation and plant upsets including variations of the demulsifier chemical dosage or tripping of the electrostatic coalescer grids inside a large dehydrator vessel operated on a crude oil production field in Saudi Arabia. It is demonstrated that DDD data can provide a detailed understanding of the oil–water separation phenomena occurring inside the dehydrator vessel, which helped in planning process recovery strategies in the event of a plant upset.     

An adaptive step-down procedure for fault variable identification

In a process with a large number of process variables (high-dimensional process), identifying which variables cause an out-of-control signal is a challenging issue for quality engineers. In this paper, we propose an adaptive step-down procedure using conditional T² statistic for fault variable identification. While existing procedures focus on selecting variables that have strong evidence of a change, the proposed step-down procedure selects a variable having the weakest evidence of a change at each step based on the variables that are selected in previous steps. The information of selected unchanged variables is effectively utilised in obtaining a powerful conditional T² test statistic for identifying the changed elements of the mean vector. The proposed procedure is designed to utilise the correlation information between fault and non-fault variables for the efficient fault variables identification. Further, the simulation results show that the proposed procedure has the better diagnostic performance compared with existing methods in terms of fault variable identification and computational complexity, especially when the number of the variables is high and the number of fault variables is small.