PCR identification of ruminant tissue in raw and heat-treated meat meals

To control the spread of bovine spongiform encephalopathy in cattle through contaminated animal feedstuffs, screening of feed products is essential. We designed five pairs of primers to identify specifically raw and heat-treated tissue from cattle, sheep, goat, deer, and ruminants in general. A forward common primer was designed based on a conserved DNA sequence in the mitochondrial 12S rRNA-tRNA(val)-16S rRNA gene, and reverse primers were designed to hybridize with a species-specific DNA sequence for each species considered. All primers were developed to create a specific PCR product small enough (less than 200 bp) to be suitable for heat-treated material. To evaluate the effect of heat treatment, a severe sterilization condition (133 degrees C at 300 kPa for 20 min) was chosen. Species-specific amplicons were obtained from all types of heat-treated meat meals. Analysis of laboratory-contaminated vegetable meals revealed that the detection limit of the assay was 0.05% for each species analyzed. This PCR-based analysis can be used as a routine method for detecting banned animal-derived ingredients in raw and heat-treated feedstuffs.     

Digestibility and physicochemical properties of granular sweet potato starch as affected by annealing

The effects of annealing on the digestibility, morphology, and physicochemical characteristics of four types of granular sweet potato starches [Yulmi (YM), Yeonwhangmi (YHM), sweet potato starch from Samyang Genex (SSPS), and commercial sweet potato starch (CSPS)] were investigated. Annealing was performed at 55°C and 90% moisture content for 72 h. Morphology, the branched chain distribution of amylopectin, and the X-ray diffraction pattern remained unchanged during the annealing process. The slowly digestible starch content in annealed YM, YHM, and SSPS starches increased, but did not change in annealed CSPS. The gelatinization temperatures increased, but the gelatinization temperature range decreased with annealing. The swelling factor and amylose leaching decreased, while the close packing concentration increased. Rapid Visco Analyser analysis revealed that annealed starches possessed thermal stability and higher pasting temperatures. It is suggested that the enhanced packing arrangement formed during annealing impacts the digestibility and physicochemical properties of sweet potato starches.     

Changes in S-allyl cysteine contents and physicochemical properties of black garlic during heat treatment

This study aimed to investigate the effects of temperature on the black garlic manufacturing process. The moisture content, pH, browning intensity, S-allyl cysteine (SAC) content and antioxidant activity, including DPPH radical scavenging activity and reducing power, were determined. The moisture content of garlic gradually decreased throughout the heating process. The rate of moisture removal was higher at high temperatures compared with low temperatures. The pH also decreased more significantly in garlic heated at high temperatures. The browning intensity increased with increasing temperature. The SAC contents of black garlic were significantly different according to heating temperature; the garlic samples heated at a low temperature had a higher SAC contents. Antioxidant activity, as determined by the DPPH radical scavenging activity and reducing power, increased when the garlic was exposed to higher temperatures.     

Development and characterization of covalently cross-linked SPEEK/Cs-TPA/CeO2 composite membrane and membrane electrode assembly for water electrolysis

Covalently cross-linked SPEEK/Cs-TPA/CeO₂ composite membrane was prepared for the polymer electrolyte membrane water electrolysis. Tungstophosphoric acid (TPA) with a cesium was added to the SPEEK to increase proton conductivity. CeO₂ was used to scavenge free radicals which attack the membrane in the water electrolysis and to improve the durability of the membrane. The composite membrane featured the electrochemical characteristics, such as 0.130 S/cm of proton conductivity at 80 °C, and 2.324 meq./g-dry-memb. of ion-exchange capacity. Pt(NH₃)₄Cl₂, Pd(NH₃)₄Cl₂, RhCl₃ and Co(NH₆)₄Cl₃ were used to prepare a variety of the membrane electrode assemblies (MEAs) as electrocatalytic precursors. Electrochemical activity surface area (ESA) of the Pt–Pd electrode prepared with 2 mM Pt(NH₃)₄Cl₂ and 2 mM Pd(NH₃)₄Cl₂ showed the best properties of 26.2 m²/g with CL-SPEEK/Cs-TPA/CeO₂ membrane. In water electrolysis performance, the cell voltage of Pd/PEM/Pt–Pd MEA with CL-SPEEK/Cs-TPA/CeO₂(1%) composite membrane showed cell property of 1.82 V at 1 A cm⁻² and 80 °C.     

Periodic Exposure of Plasma-Activated Medium Alters Fibroblast Cellular Homoeostasis

Excess amounts of redox stress and failure to regulate homeostatic levels of reactive species are associated with several skin pathophysiologic conditions. Nonmalignant cells are assumed to cope better with higher reactive oxygen and nitrogen species (RONS) levels. However, the effect of periodic stress on this balance has not been investigated in fibroblasts in the field of plasma medicine. In this study, we aimed to investigate intrinsic changes with respect to cellular proliferation, cell cycle, and ability to neutralize the redox stress inside fibroblast cells following periodic redox stress in vitro. Soft jet plasma with air as feeding gas was used to generate plasma-activated medium (PAM) for inducing redox stress conditions. We assessed cellular viability, energetics, and cell cycle machinery under oxidative stress conditions at weeks 3, 6, 9, and 12. Fibroblasts retained their usual physiological properties until 6 weeks. Fibroblasts failed to overcome the redox stress induced by periodic PAM exposure after 6 weeks, indicating its threshold potential. Periodic stress above the threshold level led to alterations in fibroblast cellular processes. These include consistent increases in apoptosis, while RONS accumulation and cell cycle arrest were observed at the final stages. Currently, the use of NTP in clinical settings is limited due to a lack of knowledge about fibroblasts’ behavior in wound healing, scar formation, and other fibrotic disorders. Understanding fibroblasts’ physiology could help to utilize nonthermal plasma in redox-related skin diseases. Furthermore, these results provide new information about the threshold capacity of fibroblasts and an insight into the adaptation mechanism against periodic oxidative stress conditions in fibroblasts.     

A study on methane–air premixed flames interacting with syngas–air premixed flames

Numerical study on the interaction between methane–air and syngas–air premixed flames is conducted according to equivalence ratio and global strain rate in detailed chemistry. This study targets at understanding of an interacting combustion system as an alternative retrofit concept where one can modify the existing facilities minimally in industrial and power plant burners in order to reduce the emission of carbon dioxide. It is seen that methane premixed flame interacting with syngas premixed flame can be sustained even over the rich flammable limit of single methane premixed flame. The inspection of detailed flame structure such as the distributions of major species and chain carrier radicals, flame separation distance, spatial flow velocity, and spatial distribution of the rate of production and consumption of CH₄, H₂, and CO is also conducted to depict the flame interactions. The importance of global strain rate and thus the flame separation distance in the enhanced burning of methane premixed flame is also stressed through the inspection of the consumption rates of H₂, CO, and CH₄. Anomalous phenomena such as the migration of premixed flame cross the stagnation plane and the nearly constant flame separation distance are also discussed.     

Evaluation of Enhanced Heat Transfer Within a Four Row Finned Tube Array of an Air Cooled Steam Condenser

Air cooled steam condensers (ACSC) consist of finned-tube arrays bundled in an A-frame structure. Inefficient performance under extreme temperature operating conditions is a common problem in ACSCs. The purpose of this study was to improve the heat transfer characteristics of an annular finned-tube system for better performance in extreme climatic conditions. Perforations were created on the surface of the annular fins to increase heat transfer coefficient (h). Mesh generation and finite volume analyses were performed using Gambit 2.4.6 and Fluent 6.3 with an RNG k–? turbulent model to calculate pressure drop (ΔP), heat flux (q), and heat transfer coefficient (h). Solid (no perforations) finned-tubes were simulated with free stream velocity ranging between 1 m/s–5 m/s and validated with the published data. Computations were performed for perforations at 30° interval starting at ±60°, ±90°, ±120°, ±150°, and ±180° from the stagnation point. Five cases with single perforation and three cases with multiple perforations were evaluated for determining the maximum q and h, as well as minimum ΔP. For the perforated case (perforations starting from 60° at interval of 30°), the fin q and h performance ratios increased by 5.96% and 7.07%, respectively. Consequently, the fin ΔP performance ratio increased by 11.87%. Thus, increased q and h is accompanied with a penalty of higher ΔP. In contrast, a single perforation location at 120° provided favorable results with a 1.70% and 2.23% increase in q and h performance ratios, respectively, while there was a relatively smaller increase (only 1.39%) of ΔP performance ratio. Perforations in the downstream region at ±120°, ±150°, and ±180° also resulted in a similar favorable outcome. Furthermore, the spacing of the fins along the arms of an A-frame ACSC was altered to decrease ΔP across the finned-tube array. Fin spacing in the A-frame structure with sparsely spaced fins in the center resulted in a 1.80% reduction in ΔP. Thus, penalty in ΔP for a perforated fin can possibly be offset by changing the fin spacing along the arms of an A-frame structure.     

LOFT L9-3 Experiment Simulation Using the SPACE Code

The KHNP （Korea Hydro ＆ Nuclear Power Co.） has developed a multipurpose nuclear safety analysis code called SPACE （the safety and performance analysis code） for nuclear power plants. SPACE code is a best-estimated two-phase three-field thermal-hydraulic analysis code used to analyze the safety and performance of pressurized water reactors. In this paper, LOFT （loss of fluid test） L9-3 experiment using the SPACE code was selected to confirm the capability of SPACE code and the results calculated by the SPACE code are compared with those measured through the experiment. The results were compared with the experimental data and those of the other code simulations. Throughout the simulation result, it was concluded that the SPACE code can effectively simulate LOFT L9-3 experiment.     

A heuristic method of variable selection based on principal component analysis and factor analysis for monitoring in a 300 kW MCFC power plant

In a commercialized 300 kW molten carbonate fuel cell (MCFC) power plant, a univariate alarm system that has only upper and lower limits is usually employed to identify abnormal conditions in the system. Even though univariate alarms have already been adopted for system monitoring, this simple monitoring system is limited for using in an extended monitoring system for fault diagnosis. Therefore, based on principal component analysis (PCA), a recursive variable grouping method for a multivariate monitoring system in a commercialized MCFC power plant is presented in this paper. In terms of development, since a principal component analysis model that contains all system variables cannot isolate a system fault, heuristic recursive variable selection method using factor analysis is presented here. To verify the performance of the fault detection, real plant operations data are used. Furthermore, comparison between type 1 and type 2 errors for four different variable groups demonstrates that the developed heuristic method works well when system faults occur. These monitoring techniques can reduce the number of false alarms occurring on site at MCFC power plant.     

Integrated carbon composite bipolar plate for polymer–electrolyte membrane fuel cells

The electrical resistance of bipolar plates for polymer–electrolyte membrane fuel cells (PEMFCs) should be very low to conduct the electricity generated with minimum electrical loss. The resistance of a bipolar plate consists of the bulk material resistance and the interfacial contact resistance when two such plates are contacted to provide channels for fuel and air (oxygen) supplies.