• Analytical Science and Technology
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• v.35 no.5
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• pp.212-217
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• 2022

In this study, ozone (O₃) samples were prepared for investigating the heterogeneous reactions between O₃ and tropospheric aerosols and were characterized by spectroscopic methods. O₃ generated from an ozone generator was purified by selective adsorption on refrigerated silica gel, followed by transfer to a sample bulb. The amount of UV light (λ = 256 nm) absorbed by O₃ was measured as a function of time at two different temperatures (room temperature and 50 ℃) and under different irradiation conditions. A correlation plot of 1/[O₃] versus time showed that O₃ decomposition follows the 2^nd order reaction rate under a steady-state approximation. The initial concentration of O₃, observed rate constants (k_obs), and the half-life of O₃ in the sample stored at room temperature were determined to be 2.74 [±0.14] × 10¹⁶ molecules·cm^-3, 4.47 [±0.64] × 10^-23 molecules^-1·cm³·s^-1, and 9.5 [±1.4] days, respectively. The evaluation of O₃ stability under various conditions indicated that special care should be taken to prevent the exposure of the O₃ samples to hightemperature environment and/or UV radiation. This study established a protocol for the preparation of highly purified O₃ samples and confirmed that the O₃ samples can be stored for a day after preparation for further experiments.

• Analytical Science and Technology
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• v.36 no.1
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• pp.32-43
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• 2023

This study reports for the first time about a stability indicating RP-HPLC method for qualitative and quantitative determination of acalabrutinib in bulk and dosage form and in presence its impurities 1, 2 and 3. The chromatographic separation was carried on Zorbax XDB-C18 (250×4.6 mm; 5 µ id) as stationary phase, Phosphate buffer pH 6.4 and methanol 80:20 (v/v) as mobile phase at a flow rate of 1.0 mL/min, UV detection was carried at wavelength of 238 nm and the analysis was completed with a run time of 15 min. In these conditions the retention time of acalabrutinib and its impurities 1, 2 and 3 was observed to be 3.50, 4.83, 8.40 and 9.93 min respectively. The method was validated for system suitability, range of analysis, precision, specificity, stability and robustness. Spiked recovery at 50 %, 100 % and 150 % was carried for both standard and impurities and the acceptable % recovery of 98-102 was observed for acalabrutinib and both impurities studied and the % RSD in each spiked level was found to be less than 2. Stability tests were done through exposure of the analyte solution to five different stress conditions i.e expose to 1N hydrochloric acid, 1 N sodium hydroxide, 3 % peroxide, 80 ℃ temperature and UV radiation at 254 nm. In all the degradation condition, standard drug acalabrutinib was detected along with both the impurities studied and the degradation products were successfully separated. In the formulation analysis there is no other chromatographic detection of other impurities and formulation excipients. Hence the developed method was found to be suitable for the quantification of acalabrutinib and can separate and analyse impurities 1 and 2.

• Conservation Science in Museum
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• v.26
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• pp.25-34
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• 2021

3D printing technology has been actively applied for the restoration of cultural properties. However, its application to the restoration of glass cultural properties has not yet been reported and thus requires further study. In this study, 3D printing technology was used to restore a defective part of a glass sarira bottle that forms an element of a series of sarira reliquaries commissioned by Yi Seonggye (known as King Taejo after founding the Joseon Dynasty) that was excavated from Geumgangsan Mountain (designated as Treasure No. 1925) and is currently housed at the National Museum of Korea. The defective area was reproduced using 3D printing and the printed reproduction was reproduced again using an epoxy resin. This latter piece was used as the restoration component rather than the 3D printed element. After the completion of the conservation treatment, the materials used for the 3D printing were compared with transparent materials used to restore ceramics to evaluate their usability and stability. A total of five specimens were produced, including from photocurable resin made by a stereo lithography apparatus (SLA), epoxy resin, acrylic resin, and more. They were exposed to UV for 96 hours to test for yellowing. Of the two specimens made of photocurable resins and exposed to UV, one was sprayed with a UV blocking agent but the other was exposed as-is. The UV exposure test showed that the specimen made by the SLA and sprayed with a UV blocking agent and the specimen made of epoxy resin were stable in terms of yellowing with a change in the b-value was less than 1. They are thus considered to be suitable materials for the restoration of glass cultural properties. Such glass cultural properties are often diverse in shape and their restoration can be difficult as they generally consist of a range of complex parts that hamper restoration. In this regard, diverse materials should be considered when selecting materials for the restoration of glass cultural properties.

• Food Science and Biotechnology
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• v.15 no.1
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• pp.5-12
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• 2006

Degradation performance of environmentally friendly plastics that can be disintegrated by combination of sunlight, microbes in soil, and heat produced in landfills was evaluated for use in industries. Two multi-degradable master batches (MCC-101 and MCC-102 were manufactured, separately mixed with polyethylene using film molding machine to produce 0.025 mm thick films, and exposed to sunlight, microbes, and heat. Low- and high-density polyethylene (LDPE and HDPE) films containing MCC-101 and MCC-102 became unfunctional by increasing severe cleavage at the surface and showed high reduction in elongation after 40 days of exposure to ultraviolet light. LDPE and HDPE films showed significant physical degradation after 100 and 120 days, respectively, of incubation at $68{\pm}2^{\circ}C$. SEM images of films cultured in mixed mold spore suspension at $30^{\circ}C$ and 85% humidity for 30 days revealed accelerated biodegradation on film surfaces by the action of microbes. LDPE films containing MCC-l01 showed absorption of carbonyls, photo-sensitive sites, at $1710\;cm${-1}$ when exposed to light for 40 days, whereas those not exposed to ultraviolet light showed no absorption at the same frequency. MCC-101-based LDPE films showed much lower $M_w$ distribution after exposure to UV than its counterpart, due to agents accelerating photo-degradation contained in MCC-101.

• Environmental Analysis Health and Toxicology
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• v.11 no.1_2
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• pp.1-10
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• 1996

A decrease in stratospheric ozone probably caused by chloroflurocarbons (CFCs) emissions, has been observed large parts of-the globe. It is generally accepted that if ozone levels in the stratosphere are depleted, greater amounts of shortwave ultraviolet radiationB (UVB) will reach the earth's surface, resulting in increased incidence of nonmelanoma skin cancer. In this study, we evaluated several mathematical models, such as a power and an exponential model, and a geometric model considering the surface area of a human body part and ages for the prediction of Skin cancer incidence caused by exposure to the UVB radiation. These models basically estimated the risk of skin cancer based on those measurements of the local ozone in stratosphere and UVB. Both were measured at a part of Seoul with a Dobson ozone spectrometer and Robertson-Berger UV Biometer for 1995. As a result, we calculated the point estimation applying a biological amplification factor (BAF), UVB radiation and other factors. We used a Monte-Carlo simulation technique with assumption on the distribution of each considered factor. The sensitivity analysis of model by there components conducted using Gaussian sensitivity method. The annual integral of UVB radiation was 2275 MED (minimal erythema dose)/yr. Also, an estimate of the annual amount of UVB reaching the earth's surface at a korea's latitude and altitude was 3328 MED/yr. The values of the radiation amplification factor (RAF) were ranged from 0.9 to 1.5 in Seoul. To give the effective factors required to model the prediction of skin cancer incidence caused by exposure to the UVB radiation in Korea, we studied the pros and cons of above mentioned models with the application of those parameters measured in Seoul, Korea.

• Journal of Microbiology and Biotechnology
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• v.29 no.9
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• pp.1349-1360
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• 2019

Chronic exposure to ultraviolet (UV) radiation, regarded as a major cause of extrinsic aging or photoaging characterized by wrinkle formation and skin dehydration, exerts adverse effects on skin by causing the overproduction of reactive oxygen species. Agastache rugosa Kuntze, known as Korean mint, possesses a wide spectrum of biological properties including anti-oxidation, anti-inflammation, and anti-atherosclerosis. Previous studies have reported that A. rugosa protected human keratinocytes against UVB irradiation by restoring the anti-oxidant defense system. However, the anti-photoaging effect of A. rugosa extract (ARE) in animal models has not yet been evaluated. ARE was orally administered to hairless mice at doses of 100 or 250 mg/kg/day along with UVB exposure for 12 weeks. ARE histologically improved UVB-induced wrinkle formation, epidermal thickening, erythema, and hyperpigmentation. In addition, ARE recovered skin moisture by improving skin hydration and transepidermal water loss (TEWL). Along with this, ARE increased hyaluronic acid levels by upregulating HA synthase genes. ARE markedly increased the density of collagen and the amounts of hydroxypoline via two pathways. First, ARE significantly downregulated the mRNA expression of matrix metalloproteinases responsible for collagen degradation by inactivating the mitogen-activated protein kinase/activator protein 1 pathway. Second, ARE stimulated the transforming growth factor beta/Smad signaling, consequently raising the mRNA levels of collagen-related genes. In addition, ARE not only increased the mRNA expression of anti-oxidant enzymes but also decreased inflammatory cytokines by blocking the protein expression of nuclear factor kappa B. Collectively, our findings suggest that A. rugosa may be a potential preventive and therapeutic agent for photoaging.

• Journal of the Korean institute of surface engineering
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• v.55 no.6
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• pp.353-362
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• 2022

Recently, transmittance of photomasks for ultra-violet (UV) region is getting more important, as the light source wavelength of an exposure process is shortened due to the demand for technologies about high integration and miniaturization of devices. Meanwhile, such problems can occur as damages or the reduction of yield of photomask as electrostatic damage (ESD) occurs in the weak parts due to the accumulation of static electricity and the electric charge on chromium metal layers which are light shielding layers, caused by the repeated contacts and the peeling off between the photomask and the substrate during the exposure process. Accordingly, there have been studies to improve transmittance and antistatic performance through various functional coatings on the photomask surface. In the present study, we manufactured antireflection films of Nb₂O₅, | SiO₂ structure and antistatic films of ITO designed on 100 × 100 × 3 mmt sodalime glass by DC magnetron sputtering system so that photomask can maintain high transmittance at I-line (365 nm). ITO thin film deposited using In/Sn (10 wt.%) on sodalime glass was optimized to be 10 nm-thick, 3.0 × 103 𝛺/☐ sheet resistance, and about 80% transmittance, which was relatively low transmittance because of the absorption properties of ITO thin film. High average transmittance of 91.45% was obtained from a double side antireflection and antistatic thin films structure of Nb₂O₅ 64 nm | SiO₂ 41 nm | sodalime glass | ITO 10 nm | Nb₂O₅ 64 nm | SiO₂ 41 nm.

• Journal of agriculture & life science
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• v.53 no.3
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• pp.17-26
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• 2019

Chamaecyparis obtusa is one of the economical conifers planted in Korea due to its good quality timber and wood characteristics. Individuals of C. obtusa containing high terpenes (HT) and low terpenes (LT) were selected for by colorimetric method. The HT of C. obtusa was delayed in wilting against various abiotic stresses compared to the LT plants. The HT group exposed to UV did not significant influence the chlorophyll content, and the chlorophyll value was higher in the HT group than the LT group. Also, chilling treatment (5℃) did not significant influence on the chlorophyll content. However treatment at -4℃ showed relatively low chlorophyll content in the LT group than the HT group. Plants exposure to high temperature was not a difference between the HT and the LT group. However, treatment at 38℃ influenced the chlorophyll content that was increased exposure time-dependently. In salt treatments, chlorophyll in the HT group was lower at high concentrations (300 and 500 mM) of NaCl. However, chlorophyll content increased to slightly in treatment time-dependently, which is 6.7% to 40%. H2O2 treatment has been a negative effect on the chlorophyll content in the HT group. All concentration of H2O2 decreased the chlorophyll content of 5% to 35%. Plants containing high terpenoids were resisted against some abiotic stress such as salt and H2O2. Our results implied that terpenoids could cause various abiotic stress resistance. These results could be utilized for efficient management and biomass production during forest silvicultures.

• Design & Manufacturing
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• v.15 no.4
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• pp.65-71
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• 2021

In the early days of laser invention, it was simply used as a measuring tool, but as lasers became more common, they became an indispensable processing tool in the industry. Short-wavelength lasers are used to make patterns on wafers used in semiconductors depending on the wavelength, such as CO2 laser, YAG laser, green laser, and UV laser. At first, the hole of the PCB board mainly used for electronic parts was not thin and the hole size was large, so a mechanical drill was used. However, in order to realize product miniaturization and high integration, small hole processing lasers have become essential, and pattern exposure for small hole sizes has become essential. This paper intends to analyze the characteristics through patterns by exposing the PCB substrate through DMD and polygon scanner, which are different optical systems. Since the optical systems are different, the size of the patterns was made the same, and exposure was performed under the optimal conditions for each system. Pattern characteristics were analyzed through a 3D profiler. As a result of the analysis, there was no significant difference in line width between the two systems. However, it was confirmed that dmd had better pattern precision and polygon scanner had better productivity.

• Safety and Health at Work
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• v.13 no.4
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• pp.421-428
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• 2022

Background: The exposure to solar ultraviolet radiation is a significant risk factor generally underestimated by outdoor workers and employers. Several studies have pointed out that occupational solar exposure increased eye and skin diseases with a considerable impact on the lives and productivity of affected workers. The main purpose of this study was to evaluate the effectiveness against ultraviolet radiation of some measures recently undertaken for the protection of lifeguards in a coastal area of Tuscany. Methods: Different shading structures (gazebos and beach umbrella) were tested during a sunny summer's day on a sandy beach by means of two radiometers; the UV protection offered by some T-shirts used by lifeguards was also tested in the laboratory with a spectrophotometer. Results: The analysed shading structures strongly reduced the ultraviolet radiation by up to 90%, however a not always negligible diffuse radiation is also present in the shade, requiring further protective measures (T-shirt, sunglasses, sunscreen, etc.); the tested T-shirts showed a very good-excellent protection according to the Australian/New Zealand standard. Conclusion: Results obtained in this study suggest how the adoption and dissemination of good practices, including those tested, could be particularly effective as a primary prevention for lifeguards who are subjected to very high levels of radiation for long periods.