Antimicrobial effect of κ-carrageenan-based edible film containing ovotransferrin in fresh chicken breast stored at 5 °C

The antimicrobial activity of κ-carrageenan-based film (κCF) containing ovotransferrin (OTf) against Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, and Candida albicans was investigated. The effects of packaging with κCF–OTf on fresh chicken breast were also investigated during storage at 5 °C. The κCF–OTf showed a slight antimicrobial activity against E. coli (diameter of inhibition zone was <2 mm), but the effect was increased synergistically in the presence of 5 mM EDTA (diameter of inhibition zone is 2–5 mm). However, there were only weak inhibitory effects against S. aureus and S. typhimurium (diameter of inhibition zone was <2 mm). The growth of total microbes and E. coli in fresh chicken breast wrapped with κCF showed 1.8 and 2.7 decimal reductions by the addition of 5 mM EDTA or 5 mM EDTA in combination with 25 mg of OTf (P < 0.05), respectively, when compared to that of control at day 7. The chicken breast wrapped with κCF–PS–EDTA was also inhibited the growth of total microbes and E. coli during storage period. However, the addition of either 25 mg of OTf alone or 10 mg of potassium sorbate alone slightly inhibited the growth of microorganisms in chicken breast. Based on the obtained results, the κ-carrageenan-based film containing ovotransferrin combined with EDTA can be used for extending shelf life of fresh chicken breast.     

Preparation of conductive nylon 6 film

Electrically conducting nylon 6 films was prepared by introducing amide group or cyan group into the nylon 6 film and then introducing Cu_xS, which is known as the p-type semiconductor, into the grafted nylon films. The graft copolymerization of acrylamide (AM) and acrylonitrile (AN) onto nylon 6 film was investigated using ceric salt as the initiator. The graft yield was influenced by the concentration of ceric salt, sulfuric acid and monomer, and the reaction time. The optimum conditions for the introducing of Cu_xS were studied. Electrical conductivity of Cu_xS-treated nylon film was found to be higher by order of 10⁹ than that of the original nylon 6 film, and then properties of the resulting modified films were investigated.     

Using manual and automated annotations to search images by semantic similarity

Finding semantically similar images is a problem that relies on image annotations manually assigned by amateurs or professionals, or automatically computed by some algorithm using low-level image features. These image annotations create a keyword space where a dissimilarity function quantifies the semantic relationship among images. In this setting, the objective of this paper is two-fold. First, we compare amateur to professional user annotations and propose a model of manual annotation errors, more specifically, an asymmetric binary model. Second, we examine different aspects of search by semantic similarity. More specifically, we study the accuracy of manual annotations versus automatic annotations, the influence of manual annotations with different accuracies as a result of incorrect annotations, and revisit the influence of the keyword space dimensionality. To assess these aspects we conducted experiments on a professional image dataset (Corel) and two amateur image datasets (one with 25,000 Flickr images and a second with 269,648 Flickr images) with a large number of keywords, with different similarity functions and with both manual and automatic annotation methods. We find that Amateur-level manual annotations offers better performance for top ranked results in all datasets (MP@20). However, for full rank measures (MAP) in the real datasets (Flickr) retrieval by semantic similarity with automatic annotations is similar or better than amateur-level manual annotations.     

Fluid-structure interaction analysis for pressurizer surge line subjected to thermal stratification

Serious mechanical damages such as cracks and plastic deformations due to excessive thermal stress caused by thermal stratification have been experienced in several nuclear power plants. In particular, the thermal stratification in the pressurizer surge line has been addressed as one of the significant safety and technical issues. In this study, a detailed unsteady computational fluid dynamics (CFD) analysis involving conjugate heat transfer analysis is performed to obtain the transient temperature distributions in the wall of the pressurizer surge line subjected to stratified internal flows either during out-surge or in-surge operation. The thermal loads from CFD calculations are transferred to the structural analysis code which is employed for the thermal stress analysis to investigate the response characteristics, and the fatigue analysis is ultimately performed. In addition, the thermal stress and fatigue analysis results obtained by applying the realistic temperature distributions from CFD calculations are compared with those by assuming the simplified temperature distributions to identify some requirements for a realistic and conservative thermal stress analysis from a safety point of view.     

Study on modal characteristics of perforated shell using effective Young's modulus

For the perforated cylindrical shell submerged in fluid, it is almost impossible to develop a finite element model due to the necessity of the fine meshing of the shell and the fluid at the same time. This necessitates the use of solid shell with effective material properties. Unfortunately the effective elastic constants are not found in any references even though the ASME code is suggesting those for perforated plate. Therefore in this study the effective material properties of perforated shell are suggested by performing several finite element analyses with respect to the ligament efficiencies.     

Dynamic characteristics of steam generator U-tubes with defect

This study investigates the fluid elastic instability characteristics of steam generator (SG) U-tubes with defect and the safety assessment of the potential for fretting-wear damages caused by foreign object in operating nuclear power plants. To get the natural frequency, corresponding mode shape and participation factor, modal analyses are performed for the U-tubes either with axial or circumferential flaw with different sizes. Special emphases are on the effects of flaw orientation and size on the modal and instability characteristics of tubes, which are expressed in terms of the natural frequency, corresponding mode shape and stability ratio. Also, the wear rate of U-tube caused by foreign object is calculated using the Archard formula and the remaining life of the tube is predicted, and discussed in this study is the effect of the flow velocity and vibration of the tube on the remaining life of the tube. In addition, addressed in this study is the effect of the internal pressure on the vibration and fretting-wear characteristics of the tube.     

Development of large-area composite stilbene scintillator for fast neutron detection

Fast neutron applications have gained popularity with the growth of fast neutron production facilities. Covering a larger area and/or wider angle can be one of the advantages of a fast neutron detector. In the present study, a large-area composite stilbene scintillator with the dimensions of 200 mm (D) × 20 mm (H) was fabricated to examine its scintillation properties and to evaluate its applicability to fast neutron detection. The detector response of small- and large-area composite stilbene scintillators for neutrons and gamma rays was measured and compared with that of commercial and small single-crystal stilbene scintillators. To this end, the response of each scintillator was measured for radioisotopes as well as mono-energetic neutrons generated by a Tandem accelerator. The neutron–gamma separation performance of the large-area composite stilbene scintillator was evaluated in terms of figure-of-merit (FoM) using the digital pulse shape discrimination method. The composite stilbene scintillator showed good energy linearity, as determined from its recoil proton spectra, with reasonable n–γ separation capability. The results indicated that the composite stilbene scintillator could be applied to the field of fast neutron detection, especially when a large area and/or a wide angle is to be covered and could be a good alternative to liquid scintillators.     

Performance evaluation of a downwind diffuser on vertical axis wind turbine

Research has proven that the performance of a horizontal axis wind turbine (HAWTs) can be increased significantly by the application of a diffuser. It serves as a power augmented feature to draw higher wind flow toward the HAWT. However, research on integrating a diffuser onto vertical axis wind turbines (VAWTs) is scant, where most of the available power augmentation devices used for VAWTs are the convergent duct, deflector plate, shroud, and guide vanes which are placed in a proper configuration at the upwind. In this paper, laboratory tests and computational simulations have been carried out to study the impacts of a downwind diffuser on the performance of a VAWT. The diffuser is designed with the absence of a concentrator or flange and is placed downwind of the VAWT. Parametric computational fluid dynamics (CFD) studies were carried out for the downwind diffuser length and semi-opening angle. A five-bladed H-rotor was selected as the testing wind turbine, whereas the diffuser used was made up of flat plates. Both simulations and experiment results are consistent. From the experiments, it was found that a downwind diffuser increases the VAWT performance remarkably. The diffuser-augmented VAWT produced an increment in the maximum coefficient of power of 31.42% at the TSR 0.65 to 0.75. Moreover, the diffuser induced a better self-start ability on the VAWT. The simulation showed that the flow field at the diffuser promotes a flow expansion which created a lower-pressure region at downstream that accelerates the wind toward the VAWT, hence increasing the turbine performance significantly.     

Facile synthesis of well dispersed Pd nanoparticles on reduced graphene oxide for electrocatalytic oxidation of formic acid

In present study, we report a facile synthesis of crystalline, small size Pd nanoparticles (NPs) on reduced graphene oxide (RGO) abbreviated as Pd/RGO for electrocatalytic oxidation of formic acid (FA). Here, first graphene oxide (GO) was reduced by the green method using l-ascorbic acid and citric acid and further Pd NPs were decorated on RGO by a facile method without using any reducing agents. The reduction of GO to RGO and synthesis of Pd NPs was confirmed by the X-ray diffraction (XRD) and X-ray photoelectrons (XPS) techniques. Surface morphology of Pd/RGO nanocomposite was evaluated by the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The electrocatalytic behavior of Pd/RGO nanocomposite was tested by using of cyclic voltammetric (CV) technique for electro-oxidation of FA in mixed solution of 0.5 M HCOOH + 0.5 H₂SO₄ at RT. Results shows that the higher electrocatalytic activity of Pd/RGO nanocomposite compare to Pd NPs.     

Constructal design associated with genetic algorithm to minimize the maximum deflection of thin stiffened steel plates

This paper deals with the application of stochastic technique allied to the constructal design (CD) method and computational modeling for the optimization of composed plates reinforced by stiffeners. More specifically, it seeks to determine the optimal geometric configuration of the stiffened plate that minimizes its maximum deflection. For this purpose, a simply supported rectangular plate (with no stiffeners) was adopted as a reference. Then, a set of geometric configurations was proposed, through the application of CD method, by transforming a volume fraction (ϕ) of the reference plate into longitudinal and transverse stiffeners, maintaining the total volume, in-plane dimensions, boundary conditions, and loading. Regarding the optimization procedure, the genetic algorithm (GA) was chosen as the optimization method, and the geometric parameters considered as degrees of freedom were as follows: the number of longitudinal (N_ls) and transverse (N_ts) stiffeners; the thickness of the longitudinal (t_ls) and transverse (t_ts) stiffeners; and longitudinal and transverse stiffeners' heights ratio (h_ts/h_ls). Moreover, several values of ϕ were considered. Results indicated a great influence of the geometry on the mechanical behavior of the stiffened plates, as the optimal geometric configuration obtained here led to a reduction of over 98% in the maximum deflection in comparison with the reference plate.