In this study, tungsten carbide (WC) powder was prepared using a novel recycling process for hard metal sludge that does not use ammonium paratungstate. Instead of ammonia, acid was used to remove the sodium and crystallized tungstate, resulting in the formation of tungstic acid (H2WO4). The WC powder was successfully synthesized by the carbothermal reduction of tungstic acid through H2O decomposition, reduction of WO3 to W, and formation of WC. The carbon content and holding time at the carbothermal reduction temperature were optimized to remove free carbon from the WC powder. As a result, most of the free carbon in the WC powder prepared from sludge was removed, and the content of free carbon in the synthesized WC powder was lower than that in commercial WC powder. Moreover, the crystallite size of WC prepared from H2WO4 was much smaller than that of commercial micron-sized WC powder produced from APT. The small crystallite size of WC induces grain growth during the sintering of the WC-Co composite; thus, a WC-Co composite with large WC grains was fabricated using the WC powder prepared from H2WO4. The large WC grains affected the mechanical properties of the WC-Co composite. Further, due to the large grain size, the WC-Co composite fabricated from H2WO4 exhibited a higher toughness than that of the WC-Co composite prepared from commercial WC powder.
Carbon dots (CDs) are few nanometer-sized carbon-based nanoparticles and emerging candidate materials in various fields such as biosensors and bioimaging due to their excellent optical properties and high biocompatibility. However, most CDs, emitting blue light, have limited their application in biomedical fields due to the low penetration of short-wavelength lights into the biological system. Therefore, there has been enormous need to develop long-wavelength emitting CDs. In this study, red-emitting CDs were successfully synthesized through the hydrothermal reaction of p-phenylenediamine with hydrochloric acid. In addition, the effect of the amount of hydrochloric acid on the formation of carbon dots, resulting in the variation of the chemical structures of CDs, were investigated, which was confirmed with the intensive structural analyses using infrared and X-ray photoelectron spectroscopy. It was found that the chemical structure of CDs governed their optical properties and quantum yield. Therefore, this study provides an insight into the role of acid in forming red-emitting CDs as the optimal probe for biomedical application.
The avoidance of enemy's radar detection is very important issue in the modem electronic weapon system. Researchers have studied to minimize reflected signals of radar. In this research, two types of radar absorbing structure (RAS), 'C'-type shell and 'U'-type shell, were fabricated using fiber-reinforced composite materials and their radar cross section (RCS) were evaluated. The absorption layer was composed of glass fiber reinforced epoxy and nano size carbon-black, and the reflection layer was fabricated with carbon fiber reinforced epoxy. During their manufacturing process, undesired thermal deformation (so called spring-back) was observed. In order to reduce spring-back, the bending angle of mold was controlled by a series of experiments. The spring-back of parts fabricated by using compensated mold was predicted by finite element analysis (ANSYS). The RCS of RAS shells were measured by compact range and predicted by physical optics method. The measured RCS data was well matched with the predicted data.
In this study, the acetaldehyde removal characteristics of activated carbon (AC) for air purifier filters were investigated using metal catalysts-impregnation and functional group-modification method. The AC with a high specific surface area(1700 m2/g) and micropores was prepared by KOH activation of coconut charcoal and the efficiency of catalyst and functional group immobilization was examined by varying the drying conditions within the pores after immersion. The physical properties of the prepared activated carbon were analyzed by BET, ICP, EA, and FT-IR, and the acetaldehyde adsorption performances were investigated using gas chromatography (GC) at various impregnation and modified conditions. As the concentration of impregnation solution increased, the amount of impregnated metal catalysts increased, while the specific surface area showed a decreasing trend. The adsorption tests of the metal catalyst-impregnated and functional group-modified activated carbons revealed that excellent adsorption performance in compositions MgO10@AC, CaO10@AC, EU10@AC, and H-U3N1@AC, respectively. The MgO10@AC, which showed the highest adsorption performance, had a breakthrough time of 533.8 minutes and adsorption capacity of 57.4 mg/g for acetaldehyde adsorption. It was found that the nano-sized MgO catalyst on the activated carbon improved the adsorption performance by interacting with carbonyl groups of acetaldehyde.
Journal of the Society of Cosmetic Scientists of Korea
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v.49
no.2
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pp.127-139
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2023
In this study, minoxidil, which is well known as a pharmaceutical raw material, and diaminopyrimidine oxide (DAO), which is a cosmetic raw material, were used as active ingredients to evaluate the physical properties of niosomes and compare the skin penetrations of artificial skin. To prepare niosomes of the size of nanoparticles, a high pressure homogenization method was used, and physical properties were evaluated with a zetasizer. The particle size of the noisome including the active ingredient was measured to be 99 to 123 nm according to HLB, and the zeta potential was measured in the range of -60 to -81 mV. Through DSC (differential scanning colorimetry), it was confirmed that minoxidil, a crystalline component, was uniformly dissolved in an amorphous state in niosomes. In order to confirm and compare skin penetration, it was measured by the in vitro Franz diffusion cell method, and the niosome formulation showed 3.4 times higher penetration for minoxidil and 11.1 times higher penetration for DAO than the control gel formulation. In addition, when comparing the skin penetration of minoxidil niosome and DAO niosome, a similar trend was shown, and the penetration amount of DAO was relatively high. The shapes of the niosome formulations with different HLB values were observed using Cryo-TEM, and it was confirmed that vesicles were formed in all of them and that they were intermediate between SUV (small unilamella vesicle) and LUV (large unilamella vesicle). Through this study, minoxidil, an effective drug for hair loss, and DAO, a cosmetic raw material, can be effectively delivered to the skin by encapsulating them in a noisome formulation.
Journal of the Society of Cosmetic Scientists of Korea
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v.49
no.4
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pp.299-306
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2023
In this study, exosomes were isolated by ultrafiltration from Lactobacillus rhamnosus J2K-821 and their various effects for skin were evaluated. Their size and concentration were identified 50 ~ 200 nm and 3.22 × 108 particles/mL, respectively through nanoparticle tracking analysis. In order to verify the inflammatory relief effect of Lactobacillus rhamnosus-derived exosomes (LRDEs), their nitric oxide (NO) production inhibitory ability in RAW 264.7 macrophages induced an inflammatory reaction with lipopolysaccharide (LPS) was confirmed. It was revealed that they inhibited NO production in a concentration-dependent manner. To evaluate the antioxidant activity and skin barrier improvement effect of LRDEs, their 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and hyaluronidase inhibitory activity were confirmed. It was also revealed that their activities were increased by concentration-dependent manner. Through these results, It is believed that LRDEs can be used as a effective natural cosmetic ingredient for anti-inflammation, antioxidation and skin barrier improvement.
TThis study explored the requirement of fabric sensor that can measure the motion of the joint effectively by measuring and analyzing the variation in electric resistance of a sensor in accordance with bending and stretching motion of the arm by the implementation of a motion sensor utilizing conductive fabric. For this purpose, on both sides of two kinds of knitted fabric, namely 'L' fabric and 'W' fabric Single Wall Carbon Nano-Tube(SWCNT) was coated, fabric sensor was developed by finishing them in a variety of ways, and the sensor was attached to the arm band. The fabric sensor consisted of total 48 cases, namely background fabric for coating, the method of sensor attachment, the number of layer of sensors, the length of sensor, and the width of sensor. The performance of fabric motion sensors in terms of a dummy arm, that is, a Con-Trex MJ with 48 arm bands around it was evaluated. For each arm band, a total of 48, fastened around the dummy arm, it was adjusted to repeat the bending and stretching at the frequency : 0.5Hz, ROM : $20^{\circ}{\sim}120^{\circ}$, the voltage was recorded for each case after conducting three sets of repeat measurement for a total of 48 cases. As a result of the experiment, and as a consequences of the evaluation and analysis of the voltage based on the uniformity of the base line of the peak-to-peak voltage(Vp-p), the uniformity of Vp-p within the same set, and the uniformity of the Vp-p among three sets, the fabric sensors that have been configured in SWCNT coated 'L' fabric / welding / two layers / $50{\times}5mm$, $50{\times}10mm$, $100{\times}10mm$, and SWCNT coated 'W' fabric / welding / two layers / $50{\times}10mm$ exhibited the most uniform and stable signal value within 5% of the total variation rate. Through all these results of the experiment, it was confirmed that SWCNT coated fabric was suitable for a sensor that can measure the human limb operation when it was implemented as a fabric sensor in a variety of forms, and the optimal sensor types were identified.
The Drug Delivery System (DDS) is defined as a technology for designing existing or new drug formulations and optimizing drug treatment. DDS is designed to efficiently deliver drugs for the care of diseases, minimize the side effects of drug, and maximize drug efficacy. In this study, the optimization of tripolyphosphate (TPP) concentration on the size of Chitosan nanoparticles (CNPs) produced by crosslinking with chitosan was measured. In addition, the characteristics of Fe3O4-CNPs according to the amount of iron oxide (Fe3O4) were measured, and it was confirmed that the higher the amount of Fe3O4, the better the characteristics as a magnetic drug carrier were displayed. Through the ninhydrin reaction, a calibration curve was obtained according to the concentration of γ-aminobutyric acid (GABA) of Y = 0.00373exp(179.729X)-0.0114 (R2 = 0.989) in the low concentration (0.004 to 0.02 wt%) and Y = 21.680X-0.290 (R2 = 0.999) in the high concentration (0.02 to 0.1 wt%). Absorption was constant at about 62.5% above 0.04 g of initial GABA. In addition, the amount of GABA released from GABA-Fe3O4-CNPs over time was measured to confirm that drug release was terminated after about 24 hr. Finally, GABA-Fe3O4-CNPs performed under the optimal conditions were spherical particles of about 150 nm, and it was confirmed that the properties of the particles appear well, indicating that GABA-Fe3O4-CNPs were suitable as drug carriers.
Kim, In-Young;Lee, Joo-Dong;Ryoo, Hee-Chang;Zhoh, Choon-Koo
Journal of the Society of Cosmetic Scientists of Korea
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v.30
no.2
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pp.159-165
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2004
This study described about method that forms liquid crystal gel (LCG) by main ingredient with hydrogenated lechin (HL) in O/W emulsion system. Result of stability test is as following with most suitable LCG's composition. Composition of LCG is as following, to form liquid crystal, an emulsifier used 4.0wt% of cetostearyl alcohol (CA) by 4.0wt% of HL as a booster. Moisturizers contained 2wt% of glycerin and 3.0wt% of 1,3-butylene glycol (1,3-BG). Suitable emollients used 3.0wt% of cyclomethicone, 3.0wt% of isononyl isononanoate (ININ), 3.0wt% of cerpric/carprylic triglycerides (CCTG), 3.0wt% of macademia nut oil (MNO) in liquid crystal gel formation. On optimum conditions of LCG formation, the pHs were formed all well under acidity or alkalinity conditions (pH=4.0-11.0). Considering safety of skin, pH was the most suitable 6.0${\pm}$1.0 ranges. The stable hardness of LCG formation appeared best in 32 dyne/$\textrm{cm}^2$. Particle of LCG is forming size of 1-20$\mu\textrm{m}$ range, and confirmed that the most excellent LCG is formed in 1-6$\mu\textrm{m}$ range. According to result that observe shape of LCG with optical or polarization microscope, LCG could was formed, and confirmed that is forming multi -layer lamellar type structure around the LCG. Moisturizing effect measured clinical test about 20 volunteers. As a result, moisturizing effect of LCG compares to placebo cream was increased 36.6%. This could predicted that polyol group is appeared the actual state because is adsorbed much to round liquid crystal droplets to multi-lamellar layer's hydrophilic group. It could predicted that polyol group is vast quantity present phase that appear mixed because is adsorbed to round liquid crystal to multi-lamellar layer's hydrophilic group. This LCG formation theory may contribute greatly in cosmetics and pharmacy industry development.
Journal of the Society of Cosmetic Scientists of Korea
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v.48
no.1
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pp.1-10
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2022
Customized cosmetics are continuously mentioned as a trend in the cosmetics industry to respond to the recent rapid changes in the social environment and pursue individuality and diversity. Accordingly, four types of liposome essence corresponding to skin types were prepared by varying the ratio of liposome formulation and essence formulation as a customized cosmetic base that can be easily mixed and applied at the workplace. The volatilization residues of four types of liposome essence were measured and the nanoparticle size, polydispersity index, zeta potential and viscosity according to time for 90 d were measured, and Turbiscan was measured as a method for evaluating the stability of a colloidal dispersion system. In addition, a simple usability evaluation was performed for four types of liposome essence corresponding to the skin type. As a result, the amount of volatile residue in the four types of liposome essence was increased in dry products rather than oily ones, and the particle size showed a tendency to increase with time in the range of 165 to 175 nm, increasing up to 31.5%, and the polydispersity index was 0.23 to 0.26. There was little change with time, and the zeta potential was -74 to -72 mV, showing a slight decrease with time, but there was little change to the extent of a maximum decrease of 14.0%. Viscosity showed a decreasing trend with time in the range of 2,580 ~ 3,290 cps, showing a maximum decrease of 17.5%. In the turbiscan measurement, all of the turbiscan stability index, a measure of stability, were less than 1.0, indicating dispersion stability. In the overall simple usability satisfaction evaluation for skin types (6 points), products for oily skin (5.33 ± 0.75 points) > products for medium dry skin (5.13 ± 0.95 points) > products for dry skin (5.03 ± 0.96 points) > products for oily skin (4.80 ± 1.04 points) points) were evaluated in order. The four types of liposome essence corresponding to skin types with different ratios of liposome formulation and essence formulation were physically stable, and the possibility of application as a customized cosmetic base according to skin type was confirmed.
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