• Food Science and Preservation
• /
• v.13 no.6
• /
• pp.762-768
• /
• 2006

To assess utilization of onions extract as natural food additives, ethyl acetate, ethanol and hot water extract of freeze dried onions (red, white and yellow) were exmined for their chemical component and nitrite scavenging activity. Contents of total organic acid and total free sugar were in the range of $135.4{\sim}1,2557mg%$ and $51.7{\sim}62.9%$ as dry matter bases, respectively, and then their content of three onions were higher in ethylacetate and hor water extracts than in ethanol extract. Contents of total phenol and total flavonoids were in the range of $9.3{\sim}$13.3 % and $159.8{\sim}584.1mg%$ as dry matter bases, respectively, and their content of red onion extract by three solvent were higher than those of other onion extract. Nitrite-scavenging activities (NSA) of onion extracts were increased by lowering pH and elevating onion concentrations, and their values of ethanol and hot water were about 55% in addition of 10 mg/mL of red onion extract showing that NSA of red onion was twice higher than that of the other onions. In conclusion, the result indicated that red onion extract was very effective to inhibit nitrosamine formation at low pH condition as natural nitrite scavenging agent.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2012.05a
• /
• pp.65-65
• /
• 2012

Copper zinc tin sulfide ($Cu_2ZnSnS_4$, CZTS) is a very promising material as a low cost absorber alternative to other chalcopyrite-type semiconductors based on Ga or In because of the abundant and economical elements. In addition, CZTS has a band-gap energy of 1.4~1.5eV and large absorption coefficient over ${\sim}10^4cm^{-1}$, which is similar to those of $Cu(In,Ga)Se_2$(CIGS) regarded as one of the most successful absorber materials for high efficient solar cell. Most previous works on the fabrication of CZTS thin films were based on the vacuum deposition such as thermal evaporation and RF magnetron sputtering. Although the vacuum deposition has been widely adopted, it is quite expensive and complicated. In this regard, the solution processes such as sol-gel method, nanocrystal dispersion and hybrid slurry method have been developed for easy and cost-effective fabrication of CZTS film. Among these methods, the hybrid slurry method is favorable to make high crystalline and dense absorber layer. However, this method has the demerit using the toxic and explosive hydrazine solvent, which has severe limitation for common use. With these considerations, it is highly desirable to develop a robust, easily scalable and relatively safe solution-based process for the fabrication of a high quality CZTS absorber layer. Here, we demonstrate the fabrication of a high quality CZTS absorber layer with a thickness of 1.5~2.0 ${\mu}m$ and micrometer-scaled grains using two different non-vacuum approaches. The first solution-processing approach includes air-stable non-toxic solvent-based inks in which the commercially available precursor nanoparticles are dispersed in ethanol. Our readily achievable air-stable precursor ink, without the involvement of complex particle synthesis, high toxic solvents, or organic additives, facilitates a convenient method to fabricate a high quality CZTS absorber layer with uniform surface composition and across the film depth when annealed at $530^{\circ}C$. The conversion efficiency and fill factor for the non-toxic ink based solar cells are 5.14% and 52.8%, respectively. The other method is based on the nanocrystal dispersions that are a key ingredient in the deposition of thermally annealed absorber layers. We report a facile synthetic method to produce phase-pure CZTS nanocrystals capped with less toxic and more easily removable ligands. The resulting CZTS nanoparticle dispersion enables us to fabricate uniform, crack-free absorber layer onto Mo-coated soda-lime glass at $500^{\circ}C$, which exhibits a robust and reproducible photovoltaic response. Our simple and less-toxic approach for the fabrication of CZTS layer, reported here, will be the first step in realizing the low-cost solution-processed CZTS solar cell with high efficiency.

• Korean Chemical Engineering Research
• /
• v.49 no.6
• /
• pp.804-809
• /
• 2011

Tubular $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-${\delta}$}$ membranes were prepared by extrusion. TGA results of green body membrane after extrusion showed three successive weight losses due to decomposition of organic additives and carbonate. Drying shrinkage rate of tubular $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-${\delta}$}$ membranes was no change after 68 h and higher in the membrane with large outer diameter. XRD and SEM results showed the sintered membranes were the single phase structure and dense. The stoichiometric molar ratio agreed well with composition ratio calculated by EDS results for $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-${\delta}$}$ membrane. Radial crushing strength of tubular $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-${\delta}$}$ membrane with 0.95 mm thickness was 5.7 kgf/$mm^2$ and the oxygen permeation rate of same membrane was 146.85 mL/min ($Jo_2$=2.33 mL/$min{\cdot}cm^2$) at $950^{\circ}C$. Therefore, it was known that use of vacuum pump was more effective than that of sweep gas to obtain higher oxygen permeation flux.

• Fashion & Textile Research Journal
• /
• v.23 no.2
• /
• pp.290-296
• /
• 2021

The effect of draw ratio (8, 10, 12, 14 times) and additive CaCO₃ content (0, 0.5, 1.0, 1.5, 2.0, and 3.0 wt%) on the properties of high-performance PE monofilament was investigated in this study. As the draw ratio increased (8-14 times), the melting enthalpy (ΔHf), crystallinity, specific gravity, and tensile strength increased significantly. However, the draw ratio had little effect on the melting temperature (Tm) and crystallization temperature (Tc). The seawater fastness (stain and fade) of the hydrophobic PE monofilament prepared in this study showed an excellent grade of 4-5 in all draw ratios. To investigate the effect of the additive CaCO₃ content on the properties of high-performance PE monofilament, the draw ratio was fixed at 14 times. It was found that the tensile strength of the PE monofilament sample containing 0.5 wt% of CaCO₃ was much greater compared to the sample without CaCO₃, but the elongation of the sample containing 0.5 wt% of CaCO₃ was much less than the sample with 0 wt% CaCO₃. However, in the case of the sample containing more than 0.5 wt% CaCO₃, the tensile strength slightly decreased and the elongation slightly increased as the CaCO₃ content increased. The seawater fastness (stain and fade) of the hydrophobic PE monofilament showed excellent grades of 4-5, regardless of the amount of additives. From the above results, it was found that the maximum draw ratio of 14 times with an additive of 0.5 wt% CaCO₃ are the optimal conditions for manufacturing high-performance marine fusion materials with various fineness (denier) with high strength and low elongation.

• Animal Bioscience
• /
• v.35 no.1
• /
• pp.87-95
• /
• 2022

Objective: This study was conducted to investigate the effect of associating calcium butyrate with tannin extract, compared to an antimicrobial on the growth performance, incidence of diarrhea, intestinal histology, immune-expression of cyclooxygenase-2 (COX-2) and tumor necrosis factor α (TNF-α) in piglets. Methods: Seventy-two piglets (36 barrows and 36 gilts) weaned at 28±2 d and initial body weight of 7.17±1.07 kg were allocated to 3 treatments in a randomized complete block design with 8 replicates per treatment and 3 animals per experimental unit. Treatments were composed of NC, negative control: basal diet without additives; PC, positive control: basal diet + 40 mg/kg of colistin sulfate; or BT, basal diet + calcium butyrate + tannin extract. The butyrate and tannin inclusion levels were 0.15% in the pre-starter phase and 0.075% in the starter phase. Incidence of diarrhea was monitored daily, and on d 14 and 35 of experiment, 1 animal from each experimental unit was slaughtered to collect intestinal samples. Results: No significant differences were observed for growth performance. The butyrate-and tannin-based additive resulted in reduced (p<0.05) incidence of diarrhea in piglets during d 1 to 14 and d 1 to 35 in comparison with the other treatments. Piglets that consumed the diet containing the calcium-butyrate and tannin showed a lower (p<0.05) crypt depth in the duodenum than those receiving the NC treatment at 14 d of experimentation. The BT treatment provided a lower (p<0.05) immune-expression of COX-2 at 14 d and TNF-α at 35 d in the duodenum. Conclusion: Association between calcium butyrate and tannin extract resulted in a significant decrease in the incidence of diarrhea and inflammatory process in the duodenum of piglets. Therefore, calcium-butyrate combined with tannin could be a part of an alternative program to reduce the use of antimicrobials in the diet of weaned piglets.

• Animal Bioscience
• /
• v.35 no.6
• /
• pp.838-846
• /
• 2022

Objective: Native plants can be used as additives to replace antibiotics to improve ruminant feed utilization and animal health. An experiment was conducted to evaluate the effects of Gentiana straminea (GS) on nutrient digestibility, methane emissions, and energy metabolism of Simmental calves. Methods: Thirty-two (5-week-old) male Simmental clves, with initial body weight (BW) of 155±12 kg were fed the same basal diet of concentrates (26%), alfalfa hay (37%), and oat hay (37%) and were randomly separated into four treatment groups according to the amount of GS that was added to their basal diet. The four different groups received different amounts of GS as a supplement to their basal diet during whole experiment: (0 GS) 0 mg/kg BW, the control; (100 GS) 100 mg/kg BW; (200 GS) 200 mg/kg BW; and (300 GS) 300 mg/kg BW. Results: For calves in the 200 GS and 300 GS treatment groups, there was a significant increase in dry matter (DM) intake (p<0.01), average daily gain (ADG) (p<0.05), organic matter intake (p<0.05), DM digestibility (p<0.05), neutral detergent fibre (NDF) digestibility (p<0.05), and acid detergent fibre (ADF) digestibility (p<0.05). Dietary GS supplementation result in quadratic increases of DM intake (p<0.01), ADG (p<0.05), NDF intake (p<0.05), and ADF intake (p<0.05). Supplementing the basal diet with GS significantly increased nitrogen (N) retention (p<0.001) and the ratio of retention N to N intake (p<0.001). Supplementing the basal diet with GS significantly decreased methane (CH₄) emissions (p<0.01), CH₄/BW^0.75 (p<0.05) and CH₄ energy (CH₄-E) (p<0.05). Dietary GS supplementation result in quadratic increases of CH₄ (p<0.01) and CH₄/DM intake (p<0.01). Compared with 0 GS, GS-supplemented diets significantly improved their gross energy intake (p<0.05). The metabolizable energy and digestive energy intake were significantly greater for calves in the 100 GS and 200 GS calves than for 0 GS calves (p<0.05). Conclusion: From this study, we conclude that supplementing calf diets with GS could improve utilization of feed, energy, and N, and may reduce CH₄ emissions without having any negative effects on animal health.

• Membrane Journal
• /
• v.32 no.5
• /
• pp.292-303
• /
• 2022

An eco-friendly energy conversion device without the emission of pollutants has gained much attention due to the rapid use of fossil fuels inducing carbon dioxide emissions ever since the first industrial revolution in the 18th century. Polymer electrolyte membrane fuel cells (PEMFCs) that can produce water during the reaction without the emission of carbon dioxide are promising devices for automotive and residential applications. As a key component of PEMFCs, polymer electrolyte membranes (PEMs) need to have high proton conductivity and physicochemical stability during the operation. Currently, perfluorinated sulfonic acid-based PEMs (PFSA-PEMs) have been commercialized and utilized in PEMFC systems. Although the PFSA-PEMs are found to meet these criteria, there is an ongoing need to improve these further, to be useful in practical PEMFC operation. In addition, the well-known drawbacks of PFSA-PEMs including low glass transition temperature and high gas crossover need to be improved. Therefore, this review focused on recent trends in the development of high-performance PFSA-PEMs in three different ways. First, control of the side chain of PFSA copolymers can effectively improve the proton conductivity and thermal stability by increasing the ion exchange capacity and polymer crystallinity. Second, the development of composite-type PFSA-PEMs is an effective way to improve proton conductivity and physical stability by incorporating organic/inorganic additives. Finally, the incorporation of porous substrates is also a promising way to develop a thin pore-filling membrane showing low membrane resistance and outstanding durability.

• Fisheries and Aquatic Sciences
• /
• v.25 no.12
• /
• pp.626-636
• /
• 2022

Shellfish are exoskeleton-bearing aquatic invertebrates that consume various organic and inorganic substances floating in seawater through filter feeding. Heavy metals are known as absorbed and accumulated in seawater. Some of the toxic heavy metals are highly accumulated in seawater, and exposure to them can cause a variety of risks to the human body. Since Koreans like to eat seafood, they are more likely to be exposed to contaminated seafood with heavy metals. In this study, nine types of heavy metals were analyzed on ten different shellfish species in the coastal area of South Korea. The risk assessment was also done on shellfish in which heavy metals were detected. Zinc (Zn) and copper (Cu) were identified at an average of 56.7 mg/kg (6.70 to 466 mg/kg) and 13.2 mg/kg (0.064 to 143 mg/kg), respectively. Lead (Pb) average of 0.208 mg/kg (0.000750 to 1.02 mg/kg), cadmium (Cd) average of 0.454 mg/kg (0.0388 to 1.56 mg/kg) and mercury (Hg) average of 0.0266 mg/kg (0.00548 to 0.174 mg/kg) were identified. Additionally, arsenic (As), chromium (Cr), nickel (Ni), and silver (Ag) were also identified as average concentrations of 4.02 (0.460 to 15.0 mg/kg), 0.167 (< limit of quantification [LOQ] to 0.820 mg/kg), 0.281 (< LOQ to 1.46 mg/kg), and 0.158 mg/kg (< LOQ to 1.15 mg/kg). The result indicates that the monitoring results of heavy metals in most shellfish satisfied the Korean standard. However, Pb and Cd have exceeded some foreign standards, such as the United States and the EU. The permissible human exposure calculated using the heavy metal intake and detection amount was lower than the Joint FAO/WHO Expert Committee on Food Additives human safety standard, and the risk of heavy metals from shellfish consumption was at an acceptable level.

• Applied Chemistry for Engineering
• /
• v.35 no.4
• /
• pp.303-308
• /
• 2024

Currently, lithium secondary batteries have been used as medium- or large-sized energy sources such as electric vehicles and energy storage system (ESS) due to their high energy and eco-friendly characteristics. Currently commercialized lithium secondary batteries do not fully meet the demands for high energy density and safety. Many studies on solid electrolytes are being conducted to satisfy these requirements. In order to commercialize a solid electrolyte, it is important to supplement the low ion conductivity and high interface resistance with an electrode compared to the organic liquid electrolyte. Therefore, in this study, oligo(3,4-ethylenedioxythiophene (EDOT)) is added to poly(vinyl alcohol) (PVA), which is a polymer matrix with ion conductivity and sticky characteristics, to decrease the interfacial resistance with the same type of polythiophene (PTh)-based electrode. In addition, the addition of porous silicon dioxide (SiO₂) filler improves lithium salt dissociation ability and increases ionic conductivity. And the electrochemical stability of the solid electrolyte, which has been lowered due to additives, is improved by introducing a cross-linked structure using boric acid (BA).

• Korean Journal of Organic Agriculture
• /
• v.18 no.2
• /
• pp.233-244
• /
• 2010

This experiment was conducted to evaluate two different types of feed additive as an alternative for antibiotics on growth performance and feed cost in growing and finishing pigs. One additive is an herb extract, with Fenugreek (Trigonella foenum graecum) as the main component, while the other feed additive contains aminolevulinic acid (ALA). In the first experiment, 128 grower pigs were allotted to 4 different treatment groups and replicated 4 times with 8 pigs per replicate; the trial lasted for 28 days. The positive control group (PC) which is the control group supplemented with antibiotics was significantly higher (p<0.05) in growth rate (580.6 g/d) followed by the ALA group (532.0 g/d), there was no significant differences in terms of feed intake and feed efficiency. There were marginal reductions in feed costs measured as feed cost per head in ALA and HE added diet. However, the feed cost per weight gain of ALA treatment was higher than the control group (PC) supplemented with antibiotics. In the second experiment, 80 finisher pigs were allotted to 4 treatment groups and replicated 4 times with 5 pigs per replicate; the trial lasted for 70 days. The treatment group supplemented with an herb extract (HE) had a significantly higher (p<0.05) feed intake (2,415.8 g/d) compared to the other treatment groups, but there was no significant differences in terms of growth rate and feed efficiency. Feed cost per head in HE and ALA treatments were higher than PC treatment, and feed cost per weight gain of HE was higher than PC treat (p<0.05). The results from these experiments suggests that these two types of feed additives can both be used as an alternative for antibiotics without having a negative effect on the performance of the animals. And aminolevulinic acid was good in performance and production cost of grower and finisher pigs.