A case study on detection and sizing of defects in steam generator tubes using eddy current testing

Eddy current testing (ECT) method is widely used to detect various types of defects occurring in nuclear steam generator tubes. Therefore, the reliability of its detection and sizing accuracy for defects should be validated. For this purpose, two tubes with defect signals were pulled from an operating steam generator and destructively examined. The defect type was a circumferential crack for one tube and an intergranular attack (IGA) for the other tube. The plus point coil probe showed a better capability to detect and size both a circumferential crack and a volumetric IGA than pancake and bobbin coil probe. The destructive results are correlated with the ECT results obtained during the in-service inspection.     

Antimicrobial performance of alkaline ionic fluid (GC-100X) and its ability to remove Escherichia coli O157:H7 from the surface of tomatoes

An efficacy test of GC-100X, a noncorrosive alkaline ionic fluid (pH 12) composed of free radicals and supplemented with xylitol, was carried out against six major foodborne pathogens-Staphylococcus aureus FRI 913, Salmonella enterica serovar Enteritidis ATCC 13076, S. enterica serovar Typhimurium DT104 Korean isolate, Vibrio parahaemolyticus ATCC 17803, Escherichia coli O157:H7 ATCC 43894, and Pseudomonas aeruginosa KCTC 1637-at three different temperatures (4, 25, and 36 degrees C) with or without organic load (2% yeast extract). Results revealed a more than 4-log10 (CFU/ml) reduction (1.0 x 10(4) CFU/ml reduction) against all pathogens reacted at 37 degrees C for 3 h in the absence of organic material. GC-100X solution diluted with an equal volume of distilled or standard hard water (300 ppm CaCO3) showed effective bactericidal activity, particularly against gram-negative bacteria. Washing efficacy of GC-100X solution was compared against E. coli O157:H7 on cherry tomato surfaces with those of a commercially used detergent and chlorine water (100 ppm). Viable cell counts of E. coli O157:H7 that had penetrated to the cores of tomatoes after sanitizing treatment revealed that GC-100X stock and its 5% diluted solutions had similar washing effects to 100-ppm chlorine water and were more effective than the other kitchen detergent. These results indicate that GC-100X has good bactericidal and sanitizing activities and is useful as a new sanitizer for food safety and kitchen hygiene.     

Theoretical investigation of optical wavelength conversion techniques for DPSK Modulation formats using FWM in SOAs and frequency comb in 10 gb/s transmission systems

We have investigated the wavelength conversion techniques for differential phase-shift keying (DPSK) modulation formats in 10 Gb/s transmission systems, compared with the non-return-to-zero (NRZ) modulation format. For the wavelength conversion of DPSK modulation formats, we employed the wavelength converters based on the four-wave mixing (FWM) in semiconductor optical amplifiers (SOAs) and the frequency comb generated by phase modulation. The power penalty at 10/sup -9/ bit error rate was used as a measure of the system performance degraded by the wavelength conversion. Our simulation results show that the DPSK modulation formats have a smaller power penalty than the NRZ modulation format for the wavelength conversion using the FWM effect in an SOA due to a much lower pattern effect. However, as the wavelength conversion uses the frequency comb generated by phase modulation, it has a similar power penalty compared with the NRZ modulation format. It is also shown that the DPSK modulation formats are possible to obtain the power penalty less than 0.4 dB for both wavelength conversion techniques.     

High efficiency single pulse doped Al0.60In0.40As/GaInAs/InP HEMTs for Q-band power applications

Single pulse doped, 0.2 μm-gate Al_0.60In_0.40 As/GaInAs/InP HEMTs have been fabricated and characterised. The complete process sequence for the HEMTs includes SiN_x passivation and dry etched via hole fabrication. Power measurements at 44 GHz on a 10×60 μm² device yielded 225 mW output power, 5 dB associated gain, and 39% power added efficiency. The results indicate that the single pulse doped InP-based HEMTs are suitable for high power applications at Q-band     

Guided growth of large-scale, horizontally aligned arrays of single-walled carbon nanotubes and their use in thin-film transistors

A convenient process for generating large-scale, horizontally aligned arrays of pristine, single-walled carbon nanotubes (SWNTs) is described. The approach uses guided growth, by chemical vapor deposition (CVD), of SWNTs on miscut single-crystal quartz substrates. Studies of the growth reveal important relationships between the density and alignment of the tubes, the CVD conditions, and the morphology of the quartz. Electrodes and dielectrics patterned on top of these arrays yield thin-film transistors that use the SWNTs as effective thin-film semiconductors. The ability to build high-performance devices of this type suggests significant promise for large-scale aligned arrays of SWNTs in electronics, sensors, and other applications.     

Evaluation of coagulation and PAC adsorption pretreatments on membrane filtration for a surface water in Korea: A pilot study

Application of membrane filtration has been significantly expanded throughout the world in two decades. A project was launched to facilitate the application of membrane filtration in drinking water plants in Korea in 2004. Five pilot plants each with a capacity of 500 m³/d were installed in a Gueui Drinking Water Plant. The Han River water was a main raw water source for the plants. Key parameters of the raw water were examined. The raw water characteristics are tremendously varied with seasons and rain fall, especially in terms of turbidity and algae numbers. The operation of pretreatment was of substantial importance due to the variation of the raw water. Coagulation and powdered activated carbon adsorption were performed as pretreatment options of microfiltration. The coagulant doses were optimized with increasing turbidity compared to the conventionally used operational manual. PAC adsorption was applied to overcome fouling by high algae numbers. The addition of PAC relieved the aggravation of fouling. However, the PAC addition could not stop the undergoing fouling. A set of laboratory experiments showed that the removal of floc aggregates after coagulation and PAC was critical to maintain high water flux in the membrane system.     

Effect of Dietary Red Meat on Colorectal Cancer Risk—A Review

Heme iron overload has been implicated as the main cause of the increased risk of cancer due to the consumption of red meat. However, fish and shellfish, teas, and spices contain up to five times more iron than red meat. There is insufficient evidence that iron intake in dietary red meat is the primary causal factor for colorectal cancer. In addition, harmful substances produced during the preparation of red meat, including heterocyclic amines (HCAs), polycyclic aromatic hydrocarbons (PAHs), N‐nitroso compounds, and acrylamide, are extrinsic factors that increase carcinogenicity. HCAs are produced during the cooking of red meat, poultry meat, and fish. PAHs may also be produced during the cooking of diverse food groups, such as dairy products, fruits, vegetables, and cereals. The average daily intake of red meat among Korean individuals is 62 g; the amount of PAHs entering the body via red meat is less than the average amount of PAHs the body is exposed to in the air. Therefore, it is difficult to conclude that dietary red meat is the main cause of colorectal cancer. Rather, there may be an intricate influence of multiple factors, including fruit and vegetable intake, alcohol consumption, smoking, overweight, obesity, and stress.     

Highly efficient ring-opening polymerization of tetrahydrofuran by anhydrous ferric chloride

Poly(tetramethylene ether glycol) (PTMG), widely used as a precursor in the fabrication of commodity polymers, is typically produced byacid-catalyzed polymerization of tetrahydrofuran (THF). Herein, we report a detailed investigation of the cationic ring-opening polymerization of THF catalyzed by ferric chloride (FeCl₃), which can be considered as a strong Lewisacid. The polymerization reactions were performed in the presence of acetic anhydride at 20°C with FeCl₃, which readily produced poly(tetramethylene ether glycol diester) (PTMG_DE). A maximum yield of 79.2% was obtained within 30 min using a FeCl₃ to acetic anhydride molar ratio of 5:4. The resulting polymers generally exhibited low molecular weights and a narrow polydispersity index and could be easily converted into PTMG using aqueous NaOH. In contrast with the FeCl₃-acetic anhydride system, other iron-based catalysts such as FeCl₂ and FeCl₃·6H₂O did not show any noticeable activity in the polymerization of THF. The proposed mechanism involves initiation of the acetyl cation generated by FeCl₃, propagation by nucleophilic addition of THF, and termination by the acetate anion, accounting for the high activity of the FeCl₃ catalyst for THF polymerization. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47999.     

Rice flour — A functional ingredient for premium crabstick

This study was performed to evaluate rice flour as a functional ingredient for premium crabstick and develop a commercially viable recipe. Physicochemical properties of crabstick pastes with 42% surimi, with various rice flour concentrations (0, 1, 3, and 5%), and other ingredients were evaluated. The physical properties were measured during refrigeration and frozen storage. Rice flour measured at various concentrations (5 to 40% in water) using a DSC demonstrated similar patterns with an endothermic peak at around 63.5°C. During refrigerated storage, the strength of gels increased gradually, while cohesiveness stayed mostly unchanged. During frozen storage, water retention ability (WRA) gradually decreased as freeze-thaw (F/T) cycles were extended, however the water reduction was minimized as rice flour concentration increased. The optimum level was 1% rice flour concentration for chilled and frozen crabstick. Two crabstick samples (control and 1% rice flour) demonstrated no difference in strength and cohesiveness.