Search

Multifilament continuous hollow carbon fiber tows with a honeycomb cross-section have been produced using a gel-spun bicomponent islands-in-a-sea precursor with polyacrylonitrile (PAN) as the sea component and polymethylmethacrylate (PMMA) as the sacrificial island component. The density of the hollow carbon fibers is 1.15 g/cm3, more than 30% lower compared to commercial carbon fibers. The tensile strength of these fibers is in the range of 2.3–3.0 GPa and tensile modulus between 202 and 234 GPa. The tensile strength is over 80% higher than the 1.6 GPa strength value reported earlier for hollow carbon fibers. The specific tensile strength is 30% higher than T300 carbon fibers. The specific tensile modulus is 60% higher than T300 carbon fibers and 20% higher than aerospace grade IM7 carbon fibers. The manufacturing was successfully scaled up from a single filament to 740 filament tow without affecting the carbon fiber structural parameters. The tensile strength is limited by the size of the largest defects present, estimated to be in the range of 40–65 nm for the hollow carbon fibers.

The study of lignocellulosic materials calls for understanding the structure, and function of different cellulosic materials from diverse sources to scale-up cellulosic ethanol production. For the first time, a systematic assessment of the molecular and supramolecular structure highlighting the similarities and dissimilarities of three major categories of lignocellulosic materials: wood-based (cedar and oak), energy crop (bamboo), and agricultural or forestry waste (palm) are reported. The cellulose, hemicellulose, and lignin constituents were compared for their suitability in cellulosic ethanol production. FTIR showed structural variations within the functional groups with notable OH group in the palm and CC group in cedar. From the X-ray scattering, bamboo exhibited the highest crystallinity (49.5%), and palm showed the lowest crystallinity (22.6%) and crystallite size (2.6 nm). TGA revealed high cellulose amount and stable structure for cedar and oak, and the most unstable structure in the palm, which indicates a better cellulose/hemicellulose accessibility and biodegradability for enzymatic or chemical action in the palm. This comparative assessment can greatly facilitate material selection and component mixture, for developing an efficient and cost-effective biochemical process in ethanol manufacturing.

The inter-particle interference of lignocellulosic materials describes the order of the macromolecules at a larger size scale, which can give information about the pore structure, and interface of cellulose and lignin. The pore structure and interface influence the rate of enzymatic hydrolysis and thermal decomposition in cellulosic ethanol manufacturing. In this study, the inter-particle interference of cellulose and lignin of three major categories of lignocellulosic materials: wood-based (cedar and oak), energy crop (bamboo), and agricultural or forestry waste (palm) were evaluated. Scanning electron microscopy (SEM) reveals morphological irregularities in the case of bamboo and palm, which may form nucleation sites for faster accessibility to enzyme molecules. Small-angle X-ray scattering (SAXS) shows increased power-law exponent for palm, suggesting a less clustered structure, which was consistent with the rough surface morphology as detected by the SEM. Differential Scanning Calorimetry (DSC) showed a higher temperature maximum for cedar and oak, which is indicative of higher intermolecular forces within their organic compounds, and could result in slower disintegration of the macromolecules during biochemical processing. This study will help to estimate the activity of the macromolecules and absorption capacity of lignocellulosic materials during biochemical processing.

Polyacrylonitrile (PAN)/boron nitride nanotubes (BNNTs) composite fibers were spun using gel spinning method and the resulting carbon fibers were processed after the fibers were stabilized in air and subsequently carbonized in nitrogen. PAN fibers containing 1 wt% BNNTs show comparable drawability to the control PAN fiber while the drawability of composite fibers significantly decreases as BNNT concentration increases from 1 to 5 wt%. Differential scanning calorimetry suggests that the presence of BNNTs reduces the activation energy of oxidation and crosslinking reactions but has little effect on the activation energy of cyclization reaction during stabilization. In the PAN/BNNTs based carbon fibers, the graphitic carbon structure that formed in the vicinity of BNNT was directly observed by transmission electron microscopy.

The stabilization process is an important step in converting polyacrylonitrile (PAN) to good mechanical property carbon fiber. Currently, sustainable materials, such as cellulose nanocrystals (CNCs...

Carbon nanotube/carbon (CNT/C) composites show potential for lightweight structural materials and non-metal electrical conductors for aerospace, military, and other industries where the combination of lightweight, high strength and excellent conductivity are required. Most research attempts have been reported to fabricate CNT/C composite focusing on the high CNT alignment and dense carbon matrix. However, simultaneous improvement of strength and electrical conductivity in materials still presents a great challenge. In this study, pyrolyzed polydopamine (py-PDA) with selected surface treatments is introduced as an interface enhancer between CNTs and the carbon matrix. Due to the presence of py-PDA, the effective physical interlocking and conductive pathways are rebuilt at the interface area between CNTs and carbon matrix, resulting in better load transfer and electron transport. The CNT/py-PDA/C composite fibers demonstrated remarkable improvements in electrical conductivity (2.1 × 103 S cm−1 or 228 S m2 kg−1) and tensile strength (up to 727 MPa or 790 MPa/(g·cm−3)), which should prove to be vastly advantageous as compared to the previously reported CNT/C composites. The outstanding thermal stability of fully carbonized materials is also an attractive feature. Coupled with scalable manufacturing methods, these integrated characteristics of CNT/py-PDA/C composite fiber can potentially have broad applications for lightweight structural materials and non-metal conductors.

Polyacrylonitrile (PAN) fibers containing up to 40 wt% cellulose nanocrystals (CNC) have been successfully stabilized and carbonized to make carbon fibers. Under the batch process, PAN/CNC based carbon fibers exhibit a tensile strength in the range of 1.8–2.3 GPa, and tensile modulus in the range of 220–265 GPa, which are comparable to the control PAN-based carbon fibers. Based on the transmission electron microscopy study, individually distributed CNC regions surrounded by PAN matrix were observed in the stabilized and carbonized fibers. Carbonized fibers show two distinct stabilized and carbonized regions. This study shows that biphasic carbon fibers can be made from the PAN/CNC system.

Microstructures of typical carbon fibers (CFs) from polyacrylonitrile (PAN) and pitch-based precursors were studied using a novel digital twin approach with individual carbon fibers for a local crystal scale model. The transmission electron microscopy (TEM) samples were prepared using a focused-ion beam (FIB) for both longitudinal and transverse directions of carbon fibers. Measurements of the crystal size and orientation were estimated from X-ray scattering. TEM imaging of graphitic packing facilitated further comprehension of associations between processing and final material properties, which could enable customization of microstructures for property targets. Then the detailed microstructural information and their X-ray scattering properties were incorporated into the simulation model of an individual carbon fiber. Assuming that graphene properties are the same among different forms of carbon fiber, a reasonable physics-based explanation for such a drastic decrease in strength is the dislocations between the graphitic units. The model reveals critical defects and uncertainty of carbon fiber microstructures, including skin/core alignment differences and propagating fracture before ultimate failure. The models are the first to quantify microstructures at the crystal scale with micromechanics and to estimate tensile and compressive mechanical properties of carbon fiber materials, as well as potentially develop new fundamental understandings for tailoring carbon fiber and composites properties.

Huntsman–Merrimack MIRALON® carbon nanotubes (CNTs) are a novel, highly entangled, commercially available, and scalable format of nanotubes. As-received and acid-treated CNTs were added to aerospace grade epoxy (CYCOM® 977-3), and the composites were characterized. The epoxy resin is expected to infiltrate the network of the CNTs and could improve mechanical properties. Epoxy composites were tested for flexural and viscoelastic properties and the as-received and acid treated CNTs were characterized using Field-Emission Scanning and Transmission Electron Microscopy, X-Ray Photoelectron Spectroscopy, and Thermogravimetric Analysis. Composites containing 0.4 wt% as-received CNTs showed an increase in flexural strength, from 136.9 MPa for neat epoxy to 147.5 MPa. In addition, the flexural modulus increased from 3.88 GPa for the neat epoxy to 4.24 GPa and 4.49 GPa for the 2.0 wt% and 3.0 wt% as-received CNT/epoxy composites, respectively. FE-SEM micrographs indicated good dispersion of the CNTs in the as-received CNT/epoxy composites and the 10 M nitric acid 6 h treatment at 120 °C CNT/epoxy composites. CNTs treated with 10 M nitric acid for 6 h at 120 °C added oxygen containing functional groups (C–O, C=O, and O=C–O) and removed iron catalyst present on the as-received CNTs, but the flexural properties were not improved compared to the as-received CNT/epoxy composites.

Conductive metals such as copper are heavily used as conductors or lightning protection materials in aircrafts and other industrial areas. But the high bulk density and corrosion problem make non-metal conductors with low density and corrosionresistance more promising such as carbon nanotubes (CNTs). However, the small sample size of previously reported highly conductive CNT fibers (1-2 μm in diameter) or films (less than 1 μm in thickness) limits the practical engineering applications. In this work, a macroscopic continuously stretched CNT tape was prepared with excellent CNT alignment, high conductivity, and large dimensional size (~ 9 mm in width and ~ 30 μm in thickness). Through combined post-treatments of mechanical stretching, iodine doping and polymer capping layer, the macroscopic CNT tape shows high conductivity in the range of 10,000 S/cm (the highest is ~ 13,000 S/cm) and this excellent performance is stable in open air without any sign of degradation. Various characterizations were conducted including SEM observation, Raman, TGA, PPMS, electrical, and mechanical measurements. Overall, the high conductivity was ascribed to better CNT alignment after stretching and high carrier density after iodine doping. More importantly, the substantial stability of electrical property was demonstrated, benefitting from the polymer capping layer. Additionally, this process is based on commercially available raw materials and scalable for industrial production. And the proposed method here can be readily transferred to our buckypaper (CNT sheets) with roll-to-roll production capability. Furthermore, these highly conductive CNT tape and sheet can be directly incorporated into fiber-reinforced composite to improve the conductivity which could serve multiple functionalities as structural, electromagnetic interference shielding and lightning protection materials in aircrafts. This work opens a new path to optimize the electrical performance of CNT assemblies with a wide range of engineering applications including conductive composites..

Carbon fiber is widely used reinforcement material for composite applications. Modulus and strength of carbon fiber can be tailored depending on the precursor materials and processing conditions. However, microstructure-property relationships and defects on the crystal scale induced by processing still need to be explored. We studied microstructures of two typical carbon fibers from polyacrylonitrile (PAN) and pitchbased precursor and compared with its X-ray scattering properties and preliminary simulation results including crystal size, orientation and spacing. For this purpose, transmission electron microscopy (TEM) sample was prepared using focused-ion beam (FIB) for both longitudinal and transverse directions of carbon fiber. Pitch-based carbon fiber shows large graphitic structures with triangular defects, meanwhile PAN-based carbon fiber shows smaller graphitic structures with random distribution. In the case of pitch-based carbon fiber, crystalline size ~40 nm can be observed from the low magnification TEM image. X-ray scattering pattern also exhibit the differences between two fibers. The wide-angle X-ray scattering (WAXS) pattern of each carbon fiber shows graphitic peak at 26 and that is sharper for the pitch-based carbon fiber for both radial (2) and azimuthal () direction. This corresponds to the large graphitic crystalline size and high alignment degree of fiber structures. Full-width half maximum (FWHM) of the azimuthal angle for pitch-based and PAN-based carbon fiber is 5.9 and 31.6, respectively. This confirms the high alignment degree of pitch-based carbon fiber ~ 0.99. Precise measurements of the crystal size, orientation and TEM imaging of graphitic packing allows for further comprehension of associations between processing and final material properties which will enable customization of microstructures for property targets.

Stretchable materials are indispensable for applications such as deformable devices, wearable electronics, and future robotics. However, designs for new elastomers with high stretchability have undergone only limited research. Here we have fabricated highly stretchable Ag+/polyacrylonitrile elastomer with nanoreservoirs of lubricant using cyano-silver complexes. The prepared products feature nanoconfinement structures of lubricant surrounded by polymer chains with coordination bond through chelates of cyano-silver, resulting in an enhanced stretchability of more than 600% from 2%. The elastomeric properties were investigated, and a mechanical response model was proposed, which explained the structural evolution including the polymer chain fluidity under external deformation. Also, the easy breakage and dynamic reformation of cyano-silver coordination complexes promises a strain recovery under various stretching conditions. This elastomer itself can directly work as sensors and open paths to alternative substrates for soft electronics development.

Carbon nanotube/carbon (CNT/C) composites show potential for lightweight structural materials and non-metal electrical conductors for aerospace, military, and other industries where the combination of lightweight, high strength and excellent conductivity are required. Numerous research attempts have been reported to fabricate CNT/C composite focusing on high CNT alignment and dense carbon matrix. However, simultaneous improvements for mechanically strengthening and electrically improving properties of strength and conductivity in materials still presents a great challenge. In this study, pyrolyzed polydopamine (py-PDA) with selected surface treatments is introduced as an interface enhancer between CNTs and carbon matrix. Due to the presence of py-PDA, the effective physical interlocking and conductive pathways are rebuilt at the interface area between CNTs and carbon matrix, resulting in better load transfer and electron transport. The CNT/py-PDA/C composite fibers demonstrated remarkable improvements in electrical conductivity (2.1 × 103 S cm-1) and tensile strength (up to 727 MPa), which should prove to be vastly advantageous as compared to the previously reported CNT/C composites. The outstanding thermal stability of fully carbonized materials is also an attractive feature. Coupled with scalable manufacturing methods, these integrated characteristics of CNT/py-PDA/C composite fiber can potentially have broad applications for lightweight structural materials and non-metal conductors.

Aligned carbon nanotube (CNT) sheets reinforced with silicon carbonitride were prepared by the infiltration and pyrolysis of liquid polysilazane into mechanically stretched CNTs. The resultant nanocomposites contained a high volume fraction of CNTs (60 vol%), and due to alignment, reached an electrical conductivity of up to 2.2 × 105 S m− 1. The electrical conductivity was anisotropic based upon the CNT alignment and changed from 3.3 to 9.2 after the pyrolysis process. The high electrical conductivity of the nanocomposites contributes to their potential application in electromagnetic interference shielding.

We report the synthesis of flexible ceramic composites with a high tensile strength (536.33±7.23 MPa) using carbon nanotube sheet aligned by mechanically stretching process. The process is based on the infiltration and pyrolysis of liquid ceramic precursor into aligned carbon nanotube sheet. Mechanical properties and microstructure of the resultant composites are investigated. The resultant nanocomposites maintain well-aligned carbon nanotube morphology with high volume fraction (60%) and long pullout (15 µm), contributing to a high degree of load-transfer efficiency and toughening. Flexibility test reveals that such ceramic nanocomposites retain the original mechanical properties and microstructures after one thousand repetitions of 75% bending deformation, showing excellent compliance and durability. Applications requiring materials with high flexibility and mechanical properties can benefit from this research.

The purpose of this study was to evaluate microbial populations, Hunter's color values (L⁎, a⁎, b⁎) and the sensory quality of freeze-dried miyeokguk, Korean seaweed soup, in order to use it as space food. Microorganisms were not detected in non-irradiated freeze-dried miyeokguk within the detection limit of 1.00 log CFU/g. However, the microbial population in rehydrated miyeokguk was 7.01 log CFU/g after incubation at 35 °C for 48 h, indicating that freeze-dried miyeokguk was not sterilized by heat treatment during the preparation process. Bacteria in the freeze-dried miyeokguk were tentatively identified as Bacillus cereus, B. subtilis, Enterobacter hormaechei, and Ancinetobacter genomosp. using the 16S rDNA sequencing. In samples that were gamma-irradiated above 10 kGy, it was confirmed that all microorganisms were inactivated. Hunter's color values of the samples irradiated at doses less than 10 kGy were not significantly altered from their baseline appearance (p>0.05). Sensory evaluation showed that preference scores in all sensory properties decreased when freeze-dried miyeokguk was irradiated at doses greater than 10 kGy. Therefore, the results of this study suggest that gamma irradiation at 10 kGy is sufficient to sterilize freeze-dried miyeokguk without significant deterioration in the sensory quality, and thus, the freeze-dried and irradiated miyeokguk at 10 kGy fulfills the microbiological requirements as space food.

Pork is known as an allergenic food with porcine serum albumin (PSA, 66 kDa) representing the major allergen. This study was conducted to investigate the change in antigenicity of PSA in gamma-irradiated sausage extract treated with pepsin and trypsin. Sausage products (A and B) were irradiated at 1, 3, 10, and 20 kGy. After irradiation, sausage proteins were extracted and digested with pepsin (1:200, 30 min) and trypsin (1:300, 5, 30, 60, 90, and 120 min). The binding ability of PSA in extracts of the irradiated sausages (A and B) decreased by over 3 kGy relative to the binding ability of PSA in extracts of intact sausages and showed no notable differences when the dose of radiation ranged from 3 to 20 kGy. After treatment with pepsin and trypsin, the binding ability of PSA in extracts of the irradiated sausages was decreased more relative to that of intact sausages and showed no significant differences when the period of trypsin treatment is increased or when the dose of irradiation is increased. The sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE) results indicated that there was no visible change in the intensity of the PSA band in extracts of the irradiated sausages. After pepsin and trypsin treatment, the intensity of PSA band faded with increasing doses of irradiation. In conclusion, antigenicity of PSA in pork sausages could be reduced by gamma irradiation.

Viscosity is critically important for bulgogi sauce. However, exposure to irradiation may decrease the rheological proper-ties of bulgogi sauce. This study was conducted to compare the effects of gamma irradiation (0–9 kGy) on viscosity, molec-ular weight, pH, reducing end level, and water solubility of xanthan gum, guar gum, and locust bean gum as thickeningagents/stabilizers in bulgogi sauce. The physicochemical properties of all samples changed (p

We conducted this study to determine the optimum dose of gamma irradiation needed for the sterilization of milk porridge for patients. Milk porridge, known as Tarakjuk, was irradiated with gamma ray at doses of 0, 1, 3, 5, 7, or 10 kGy. The microbial contamination, values of isolated microbe spores, color, and viscosity were measured during storage at . The initial count of total aerobic bacteria was 2.60 log CFU/g in the non-irradiated milk porridge, but coliforms, spore-forming bacteria, yeast, and molds were not detected. The total counts of aerobic and spore-forming bacteria in the non-irradiated and 1 kGy irradiated milk porridge increased with storage period. These microbes were not detected in the milk porridge irradiated with 10 kGy. The values of isolated spores from milk porridge were 2.71 kGy (in milk porridge) and 2.21 kGy (in saline solution). All CIE color increased with gamma irradiation, but the sensory value of color did not significantly change. The viscosity of the milk porridge decreased with gamma irradiation and storage period, and the decrease in viscosity with storage period became smaller as the radiation doses increased. Sensory evaluation scores of the milk porridge were above normal (4.0) when irradiated with less than 5 kGy. These results indicate that gamma irradiation could be beneficial for preparing food with higher nutrient density and lower viscosity, especially for gastric tube-fed patients.

Ecklonia cava (EC) was irradiated with γ-rays at doses of 3, 7, and 20 kGy. The extraction yields, total polyphenol content (TPC), DPPH radical scavenging activity, antimicrobial activity, and color of the EC extracts were assessed. The results showed that irradiation caused an increase in the extraction yields of ethanol and water. TPC was found to be significantly increased when EC powder was subjected to irradiation, followed by ethanol and water extraction. However, DPPH radical scavenging and antimicrobial activities were stable under all irradiation conditions. In the heat and pH stability tests, the DPPH radical scavenging activities of EC ethanol extracts were not influenced by irradiation. Irradiation caused an increase in the lightness and redness of EC extracts and decreased the yellowness. In conclusion, γ-irradiation increased the extraction yield and TPC and brightened the color, while maintaining the antioxidant and antimicrobial activities.

Off-flavor and lipid oxidation are possible defects of irradiated bulgogi. This study compared the effects of several physico-chemical treatments on microbial safety, volatiles, lipid oxidation, and sensory properties of irradiated beef bulgogi. Samples were separately irradiated with 20 kGy after each treatment such as packaging (aerobic and vacuum), antioxidants (vitamin C+α-tocopherol (0.0 and 1.0%, w/w)), charcoal teabags (0 and 0.5%), or different temperatures (room temperature, -20, and -70°C). No bacterial growth was observed (p

This study examined the effect of gamma irradiation (3-20 kGy) on the immune activity and physicochemical properties of Myagropsis myagroides (MM) water extracts. MM powder and water extracts were subjected to gamma irradiation at 3, 7, and 20 kGy. The effects of gamma-irradiated MM water extracts on splenocyte proliferation and cytokine IFN-γ and IL-2 secretion were evaluated. The gamma-irradiated MM water extracts resulted in decreased splenocyte proliferation without cytotoxicity. The IFN-γ and IL-2 secretion increased by gamma-irradiated MM water extracts with increasing irradiation dose. For MM powder, the yield and total phenolic compounds (TPC) of water extracts were increased slightly after gamma irradiation. In MM water extracts, the TPC was higher at a dose of 20 kGy, while gamma irradiation decreased the viscosity, pH, and color of the MM extracts. In conclusion, gamma irradiation improved the immunomodulatory activity of MM water extracts, overcoming its potential weakness when applied in the food industry.

This study compared the effects of autoclaving (AC; 121 C for 15 min), gamma (GR), and electron beam irradiation (EB; 0-20 kGy) on the microbial, physicochemical, and sensory properties of ready-to-eat bulgogi during storage at 35 C for 90 d. No viable cells were observed (p

This study was conducted to evaluate the combined effect of heating and γ-irradiation on the microbiological and sensory characteristics of gochujang sauce. Gochujang sauces could be sterilized by heating (HT: 121°C for 15 min) or γ-irradiation (IR: 30 kGy), but their sensory qualities were severely decreased. Otherwise, the combined treatment of heat and γ-irradiation could minimize the change of sensory qualities. Combination treatment of γ-irradiation at 17.5 kGy after heating at 100°C for 30 min (HT-IR) would be optimal. During storage the gochujang sauce samples then were analyzed to enumerate total bacterial populations, to measure pH, and Hunter’s color values, and for sensory evaluation. Any growth of total bacterial populations was not observed in HT, IR, and HT-IR (detection limited 1< log CFU/g). The pH values of gochujang sauce ranged from 4.57 to 4.75 during storage. The Hunter’s (L*, a*, and b*) values of gochujang sauce were gradually decreased during storage, regardless of treatment. Sensory characteristics and acceptance of HT and IR were significantly lower (p

Pork is an excellent source of essential nutrients such as protein. However, pork can trigger hypersensitivity and serumalbumin of pork is known as major allergen. In this study, to evaluate the effect of gamma irradiation on the allergenicity ofporcine serum albumin (PSA), PSA solution was irradiated at 3, 5, 7, 10, 15, and 20 kGy. The changes in the ability of PSAto bind IgG and patient’s serum caused by gamma irradiation were observed by ci-ELISA and immunoblotting. SDS-PAGEwas used for measuring the conformational change of gamma-irradiated PSA. The ability of 3-kGy-irradiated PSA to bindp-IgG and patient’s serum was decreased to 30% and 15%, respectively. The binding ability showed no significant differ-ences among all irradiated samples. SDS-PAGE showed that the irradiated PSA bands were degraded and aggregated.Immunoblotting of irradiated PSA revealed that IgG and patient’s serum were rarely recognized at 3 kGy. Therefore, gammairradiation could be applied to less-allergenic pork products. Key words: porcine serum albumin, allergenicity, gamma irradiation

The purpose of this study was to search for physical treatments to reduce allergenicity of pork. Physical treatments suchas heating, autoclave, microwave, sonication, and irradiat ion have been used for food processing or reduction of allergenic-ity. The porcine serum albumin ( PSA), known as a major allergen in pork, was extracted after physical treatments. The anti-genicity of pork extract s by heating (80 and 100 o C for 20 min), autoclave (121 o C for 5, 10, and 30 min), and microwave (for5 and 10 min) was significantly decreased. Especially, th e binding ability of p-IgG to pork extracts by autoclave for 30 minshowed the greatest decrease (about 3%) in physical treatments. However, the antigenicity of pork was unaffected by soni-cation and irradiation treatment. These results indicated that the autoclave treatment was the most effective method toreduce the antigenicity of pork. Key words: PSA, pork, physical treatments, antigenicity 서론 우리나라 국민 1인당 육류 소비량은 2007년 기준으로쇠고기 7.6 kg, 닭고기 8.6 kg, 돼지고기 19.2 kg임을 미루어 볼 때 돼지고기는 국내에서 가장 많이 소비되는 식육류이다. 이 외에도 돼지고기는 지난 40여 년간 가장 빠른소비 증가 추세를 나타내었는데, 1970년에서 2008년 사이1인당 돼지고기 소비량의 연평균 증가율은 5.26%로 쇠고기와 닭고기가 각각 4.86%, 4.78%를 나타난 것에 비해 높았다(Ahn and Jo, 2009).한편, 돼지고기는 쇠고기에 비하여 콜레스테롤 함량이낮으며 vitamin B군 뿐만 아니라 필수지방산인 vitamin F도 다량 함유하고 있는 식품이다(Wood

This study was conducted to examine the bleaching of an anti-inflammatory agent containing Undaria pinnatifida extract (AIAU). Brown-colored AIAU was irradiated with gamma rays at doses ranging from 10-200 kGy. Discoloring of the anti-inflammatory agent was achieved by gamma irradiation, with significantly removal by 50 kGy irradiation. The main active compound of the agent consisted of 4% U. pinnatifida extract, which inhibited inflammatory symptoms in mouse ear edema by 93%. There was no change in effects against edema, erythema, blood flow and radical scavenging activity by irradiation.

This study examined the effect of gamma irradiation on shelf-life extension and sensory characteristics of dak-galbi. Commercial dak-galbi sauce was gamma-irradiated at 0, 5, 10, 15, 20, 25, and 30 kGy. The dak-galbi sauce (200 g) was then added to diced chicken (800 g) for cooking, and the cooked dak-galbi samples in vacuum bags were stored at 35 o C for 5 d. Dak-galbi samples were analyzed on d 0, 1, 2, 3, 4, and 5 for microbial analysis (plate count agar), thiobarbituric acid (TBARS) and volatile basic nitrogen (VBN) measurements, and on d 0 for sensory evaluation. On d 0, total bacterial populations were below detection limit after dak-galbi marinated with the gamma-irradiated (≥15 kGy) sauces were cooked, and the samples marinated with higher dose irradiated dak-galbi sauce had lower (p

Addition of calcium lactate and vitamin C, a mild heating, deep-freezing, and gamma irradiation at 25 kGy were conducted to prepare Kimchi as a ready-to-eat space food. It was confirmed that the space food was sterilized by an irradiation at 25 kGy through incubation at 37 °C for 30 days. The hardness of the Space Kimchi (SK) was lower than the untreated Kimchi (CON), but higher than the irradiated Kimchi (IR). Also, this result was supported by the scanning electron microscopic observation. Sensory attributes of the SK were similar to CON, and maintained during preservation at 35 °C for 30 days. According to the Ames test, Kimchi sterilized with a high-dose irradiation exerted no mutagenic activity in the bacterial strains of Salmonella typhimurium . And, the SK was certificated for use in space flight conditions during 30 days by the Russian Institute of Biomedical Problems.

This study was conducted to determine the effects of gamma and e-beam irradiation on the quality of minced pork and pork patties. Each sample was irradiated at 5 to 20kGy, and its quality characteristics were then evaluated during storage at 30. The results of the total bacterial populations in the minced-pork and pork patty samples showed that the antimicrobial effect of gamma irradiation was superior to that of e-beam irradiation. The 2-thiobarbituric acid reactive substances (TBARS) value of all the samples significantly increased (p(brightness), (redness), and (yellowness) of the minced pork and pork patties, were increased (p

The objective of this study was investigated to apply the fucoidan and laminarin extract from low-grade Undaria pinnatifida to real food product, a pork patty. Pork patties added with fucoidan and laminarin showed lower lipid oxidation and the inhibition against lipid oxidation was shown to be dependent on the irradiation doses. The Hunter color values of pork patty added with fucoidan increased significantly with an increase of irradiation dose. The hardness profiles of the patties with fucoidan and laminarin was decreased, but the amount of water in the patties was increased. Also, the combination of gamma irradiation and addition of fucoidan and laminarin was shown to be effective for the microbiological control. These results suggested that gamma irradiation and fucoidan and laminarin treatment showed the positive effect on microbial stability and quality of the pork patty.

Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeonbuk 580-185, KoreaAbstractThe effects of γ-irradiation on antioxidant and physicochemical properties of powder and 70% fermented ethanol extracts of Ishige okamurai (I. okamurai) were investigated. In case of powder, although yields were increased, there were no significant changes in total phenolic compounds (TPC) and 2,2-diphenyl-2-picrylhy-drazyl (DPPH) radical scavenging effect by γ-irradiation at 3, 7, and 20 kGy. In case of 70% fermented ethanol extracts, the results of TPC and DPPH radical scavenging effects showed no significant changes. However, antioxidant index increased in the 20 kGy irradiated I. okamurai extracts and decreased in 3 kGy irradiated ones. The optical density value of UV spectrum at 427 nm significantly decreased depending on increasing irradiation dosage. In conclusion, irradiated extracts of I. okamurai can be applied to the food industry due to irradiation stability on antioxidant properties. Also, irradiated extracts can be more useful for food process-ing as a result of a decrease of extracts color by irradiation.Key words: Ishige okamurai, antioxidant, γ-irradiation, color

Single-walled carbon nanotube (SWCNT) buckypaper (BP) was exposed to high temperatures with electrical current-driven thermal heating either in the air or a vacuum. High electrical currents generate Joule heating and then cause breakdown of the BP in the air at over 400 °C due to rapid oxidation. In the vacuum, electrical resistive heating can generate temperatures of more than 2000 °C for the samples. Structural changes of SWCNTs after electrical current heating were observed using electron microscopy and Raman spectra. After breakdown of BP, the disorder-induced D-band increased and a smaller diameter related radial-breathing mode was reduced in the high temperature region. Structural transformations of SWCNT to other carbon nanostructures were observed after current-driven high-temperature treatment in the vacuum. In addition, surface-enhanced Raman scattering with intensity enhancement more than ten times was observed in the BP with agglomerated Fe or Ti particles.

Yukwa were added with non-fermented tea (Bucho-cha and Okro-cha), semi-fermented tea (Ooreung-cha), and fermented tea (black tea) to investigate the effect of different kinds of tea powder on quality characteristics of Yukwa during storage. Yukwa samples were used for analysis such as crude lipid, moisture, texture, antioxidative property (TBA value), and sensory test. There were no significant differences on crude lipid, moisture, and texture analysis. Green tea powder treatment showed strong antioxidant activity. In particular, antioxidant property of non-fermented tea exhibited a higher antioxidative effect than that of the other samples. Sensory evaluation showed that sensory scores of samples added with non-fermented tea were significantly higher than the other samples, indicating that the addition with 0.1% of non-fermented tea powder could contribute to the improvement of quality and shelf-life of Yukwa during storage.

In this study, the antioxidant properties and physical characteristics of irradiated Sargassum siliquastrum water extract were evaluated. Samples were irradiated with Co 60 γ-ray at doses ranging from 3 to 20 kGy. They were then analyzed to investigate antioxidant properties, including total phenolic compound content and DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity. In addition, physical properties such as viscosity and color were evaluated. The results demonstrated that total phenolic compound content and DPPH radical scavenging activity were significantly improved (p

This study was carried to investigate effects of gamma irradiation on the moisture, crude protein, crude lipid, 2-thiobarbituric acid (TBA) values, color stability, texture, and sensory properties of restructured pork jerky. Restructured pork jerky was irradiated at dose levels of 0, 3, 5, 7 and 10 kGy with a use Co-60 source. There were no significant differences in the moisture, crude protein, crude lipid contents, and TBA values. However, as doses of gamma irradiation increased, the redness (a-value) of restructure pork jerky increased whereas shear force of restructure pork jerky was decreased by gamma irradiation. Sensory evaluation showed that sensory scores were reduced by gamma irradiation. Therefore, gamma irradiation could be an effective means to improve color and texture of restructured pork jerky, but only with proper consideration for sensory quality.

Paprika oleoresin (PO) and artificial Kimchi flavor (AKF) were added to Kimchi to improve the sensory qualities deteriorated by gamma irradiation in terms of color and flavor. Optimum concentration of both PO and AKF resulting from the sensory evaluation was 0.2%. The redness and capsanthin contents of Kimchi decreased by gamma irradiation at 25 kGy during storage at . However, the redness and capsanthin contents of gamma-irradiated Kimchi was increased by the addition of 0.2% PO, and maintained during the storage at for 30 days. The result from the sensory evaluation indicated that sensory qualities of gamma-irradiated Kimchi were effectively improved by the addition of PO and AKF during storage at . Therefore, the combined treatment of additives (PO and AKF) and gamma irradiation can be considered as an effective method to improve the redness and sensory qualities of Kimchi sterilized by high-dose gamma irradiation.

This study was conducted to evaluate the combined effects of N2-packaging (N2), mild heating at 60 °C (HT) and gamma irradiation of 20 kGy (IR) on the shelf-stability and quality of Kimchi during storage at 35 °C for 30 days. Total microbes including lactic acid bacteria were sterilized perfectly by the combination treatment of HT–IR or N2–HT–IR, and the acidity of Kimchi was not changed during storage. Irradiation softened textural property of Kimchi. However, combination of N2-packaging with heating and irradiation retarded this softening of Kimchi by high dose irradiation. Organoleptic qualities were improved by the combination treatment during the storage period.

Funtionalized pentancene, 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene), field-effect transistors (FET) were made by thermal evaporation or solution deposition methods and the temperature dependent mobility was measured. The field-effect mobility (μFET) activation energy is gate voltage dependent. At low gate voltage, activated conduction is dominant with Ea ∼ 0.27 eV, slightly smaller than the bulk value, and the activation energy decreases with increasing gate voltage. This is ascribed to traps in the film. A non-monotonic temperature dependence is observed at high gate voltage (VG

This research was conducted to evaluate the changes in allergenicity of shrimp by physical treatments using competitive indirect enzyme-linked immunosorbent assay (Ci-ELISA). Shrimp was subjected to physical treatments such as high hydrostatic pressure (HHP), sonication, autoclave and microwave. Heat-stable protein (HSP) purified from raw shrimp was used as a major allergen. The binding ability of monoclonal IgG and shrimp-allergic patients` IgE to HSP treated with HHP decreased, increasing the pressure up to 400 MPa. Especially, it became less than 50% at 400 MPa. The binding ability of mAb to HSP treated with sonication (10, 20, 30 and 60 min) decreased with the treated time. Especially, it became less than 60% with the treatment for 60 min. The allergenicity change of HSP treated with autoclave and microwave little decreased. The binding ability of mAb to HSP during the treatment for 20 min became more than 70%. The results suggest that allergenicity of HSP in raw shrimp be more easily lost by HHP or sonication treatment than by autoclave or microwave treatment.

Electrical properties of 1,4-benzenedimethanethiol are measured using the electrochemically deposited platinum electrode as one of contact lead to the molecule. Temperature dependence of current-voltage characteristics were measured from room temperature to 27 K. Fowler–Nordheim type tunneling conduction below 40 K and current fluctuation at low temperature were observed. The fluctuating behavior can be understood as electromigration and/or thermal vibration of platinum atoms at the contact between the molecule and the platinum electrode.

In the electroless plating process, to omit a sensitizing process with SnCl2, we utilized amino-functional groups on polymer particles. At first, highly monodisperse functional polymer particles could be prepared by a two-step seeded polymerization of styrene, divinylbenzene, and glycidyl methacrylate. Then, surface epoxy-functional groups were converted to amino-functional groups by treating the particles with a diamine. By using these surface amino functionalities, we tried to prepare uniformly metal-coated monodisperse polymer particles by electroless plating method. The constituents of an electroless nickel solution bath are nickel salt, a reducing agent, suitable complexing agents, and stabilizers. And the metal thickness was simply controlled by changing the loading amount of substrate polymer particles. Morphological observation of nickel-plated polymer particles was conducted by using optical microscopy, scanning electron microscopy, and transmission electron microscopy. The structural composition of plated nickel was also investigated. Most of all, the function and the efficiency of the amino-functional group of polymer particles as a polymeric ligand for metal binding was elucidated. From all observations, it was evident that in the electroless metal plating process without any sensitization step, the deposition of metal clusters on substrate particles is largely dependent upon the particle surface functionality. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3801–3808, 2006

The surface modification of monodisperse-crosslinked polymeric microspheres was carried out by introducing hydroxyl groups on the surface and utilizing the redox initiation system. The emulsions of the second monomer mixture were swollen into the monodisperse PS seed particles. The hydroxyl groups were introduced by hydrolysis of the acetate groups on the surface of microspheres. Ceric ammonium sulfate in sulfuric acid solution was employed to graft the acrylic monomer onto the polymeric microspheres. The surface characteristics of the surface-modified particles were confirmed by FTIR, SEM, and TGA measurements. From the FE-TEM image, a uniform coating layer was confirmed on the surface of microsphere. In DSC analysis, only an exothermal peak appeared when high content of DVB was used in the seeded polymerization, while, Tgs emerged after hydrolysis and graft polymerization using the low content of DVB in the second monomer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1349–1356, 2006

The surface modification of monodisperse hydroxyl functionalized polymeric microspheres was carried out by utilizing a redox initiation system. Styrene, divinylbenzene and hydroxyethyl methacrylate were used as the second monomer in the seeded polymerization. An excessive amount of the second monomer emulsion was swollen into the polystyrene (PS) seed particles completely by controlling the medium solvency and swelling temperature. The hydroxyl functional groups were radicalized by the ceric ammonium nitrate in nitric acid solution, and the methyl methacrylate was reacted uniformly on the surface of microspheres. From the SEM, and FE-TEM measurements, highly monodisperse microspheres having a smooth surface, and polymethylmethacrylate (PMMA) coating layer were observed, respectively. The surface characteristics of the PS seed particles, hydroxyl functionalized and surface-modified polymeric microspheres were confirmed by utilizing FT-IR, XPS and thermal analysis.