• Restorative Dentistry and Endodontics
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• v.47 no.4
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• pp.36.1-36.17
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• 2022

Objectives: This study aimed to evaluate the effect of aging on the marginal quality of glass hybrid (GH) material used to elevate dentin gingival margins, and to analyze the consistency of the results obtained by 3 in vitro methods. Materials and Methods: Ten teeth received compound class II cavities with subgingival margins. The dentin gingival margins were elevated with GH, followed by resin composite. The GH/gingival dentin interfaces were examined through digital microscopy, scanning electron microscopy (SEM) using resin replicas, and according to the World Dental Federation (FDI) criteria. After initial evaluations, all teeth were subjected to 10,000 thermal cycles, followed by repeating the same marginal evaluations and energy dispersive spectroscopy (EDS) analysis for the interfacial zone of 2 specimens. Marginal quality was expressed as the percentage of continuous margin at ×200 for microscopic techniques and as the frequency of each score for FDI ranking. Data were analyzed using the paired sample t-test, Wilcoxon signed-rank test, and Pearson and Spearmen correlation coefficients. Results: None of the testing techniques proved the significance of the aging factor. Moderate and strong significant correlations were found between the testing techniques. The EDS results suggested the presence of an ion-exchange layer along the GH/gingival dentin interface of aged specimens. Conclusions: The marginal quality of the GH/dentin gingival interface defied aging by thermocycling. The replica SEM and FDI ranking results had stronger correlations with each other than either showed with the digital microscopy results.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2022.09a
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• pp.86-86
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• 2022

Sorghum (Sorghum bicolor) is increasingly important as a biomass crop worldwide. Its genetic diversity provides a large range of biochemical composition suitable for various uses as bioplastics. Phenolic compounds are the main compounds of lignocellulosic residues, which can be used as a source of active components for their use in active packaging materials. In this research, we investigated the total phenolic content (TPC) and the total flavonoid content (TFC) among 60 mutant lines (early heading, high biomass and dwarfness) and their original cultivars. Sixty sorghum mutant lines were developed by treatment with gamma-ray or proton irradiation in 14 sorghum cultivars. The levels of TPC and TFC of 14 original cultivars were ranging from 3.27 to 11.54 mg/100 g and 2.39 to 6.74 mg/100 g, respectively. The TPCs of the mutant lines were ranging from 1.92 to 13.10 mg/100 g with average content of 6.35 mg/100 g. The TFCs of the mutant lines were ranging from 1.72 to 8.30 mg/100 g with average content of 4.20 mg/100 g. Three mutant lines derived from gamma-ray showed significant lower TPC and TFC than those of the original cultivar. While, five mutant lines showed significant higher TPC and TFC. These findings will be useful for the selection of sorghum genotypes with improved phenolic compounds.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.4
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• pp.17-31
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• 2023

Amidst escalating global warming fueled by indiscriminate fossil fuel consumption, concerted efforts are underway worldwide to mitigate atmospheric carbon dioxide (CO₂) levels. Electrochemical CO₂ reduction technology is recognized as a promising and environmentally friendly approach to convert CO₂ into valuable hydrocarbon compounds, deemed essential for achieving carbon neutrality. Copper, among the various materials used as CO₂ reduction electrodes, is known as the sole metal capable of generating C₂₊ compounds. However, low conversion efficiency and selectivity have hindered its widespread commercialization. This review highlights diverse research endeavors to address these challenges. It explores various studies focused on utilizing copper-based electrodes for CO₂ reduction, offering insights into potential solutions for advancing this crucial technology.

• FOCUS: LIFE SCIENCE
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• no.1
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• pp.1.1-1.4
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• 2024

This article provides comprehensive guidance on the maintenance, cleaning, regeneration, and storage of silica-based HPLC (High-Performance Liquid Chromatography) columns. The general considerations emphasize the importance of using in-line filters and guard cartridges to protect columns from blockage and irreversible sample adsorption. While these measures help, contamination by strongly adsorbed sample components can still occur over time, leading to an increase in back pressure, loss of efficiency, and other issues. To maximize column lifetime, especially with UHPLC (Ultra-High Performance Liquid Chromatography) columns, it is advisable to use ultra-pure solvents, freshly prepared aqueous mobile phases, and to filter all samples, standards, and mobile phases. Additionally, an in-line filter system and sample clean-up on dirty samples are recommended. However, in cases of irreversible compound adsorption or column voiding, regeneration may not be possible. The document also provides specific recommendations for column cleaning procedures, including the flushing procedures for various types of columns such as reversed phase, unbonded silica, bonded normal phase, anion exchange, cation exchange, and size exclusion columns for proteins. The flushing procedures involve using specific solvents in a series to clean and regenerate the columns. It is emphasized that the flow rate during flushing should not exceed the specified limit for the particular column, and the last solvent used should be compatible with the mobile phase. Furthermore, the article outlines the storage conditions for silica based HPLC columns, highlighting the impact of storage conditions on the column's lifetime. It is recommended to flush all buffers, salts, and ion-pairing reagents from the column before storage. The storage solvent should ideally match the one used in the initial column test chromatogram provided by the manufacturer, and column end plugs should be fitted to prevent solvent evaporation and drying out of the packing bed.

• Advances in materials Research
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• v.13 no.3
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• pp.233-241
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• 2024

Quantitative analysis of the Zingiber Officinale sample using subcritical water extraction (SWE) was developed employing High-Performance Liquid Chromatography (HPLC) to bolster the advancement of this innovative green extraction process. This research focuses on three principal ginger bioactive compounds: 6-gingerol, 6-shagoal, and 10-gingerol. Various stages were undertaken to establish the quantitative analysis method, encompassing the optimisation of HPLC operating conditions and the formulation of standard calibration curves, yielding individual compound equations. A robust correlation within the calibration curve was achieved, exhibiting an r² value of 0.9814 and an RSD of 5.00%. A simultaneous, swift, and dependable method was established with an injection time of 20 minutes and an 8-minute delay between injections, in contrast to the previous HPLC analysis requiring a 45-minute injection time for detecting and quantifying all components. Notably, no post-treatment was applied after the SWE process. This advancement allows for potential future online measurement of Zingiber Officinale bioactive compounds extracted using subcritical water extraction through this technology.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.4
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• pp.172-179
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• 2006

When $Al_2O_3-MoO_3$ mixture is reduced, $MoO_3$ is only reduced to Mo at $900^{\circ}C$. But a compound between $Al_2O_3$ and Mo is not formed up to $1300^{\circ}C$. In the case of $Al_2O_3-MoO_3-MnO_2$ mixture, an intermediate compound $Mn_2Mo_3O_8$ is firstly formed at $900^{\circ}C$ and changes to $MnAl_2O_4$ at $1100^{\circ}C{\sim}1300^{\circ}C$. $Al_2O_3/Mo/MnO_2$ composite are manufactured by a selective reduction process in which Mo is only reduced in the powder mixture of $Al_2O_3,\;MoO_3\;and\;MnO_2$ oxide. For $Al_2O_3/Mo$ composite, the average grain size was not changed with increasing Mo content because of inhibition of grain growth of $Al_2O_3$ matrix in the presence of Mo particles. Fracture strength increased with increasing Mo content due to phenomenon of grain growth inhibition of $Al_2O_3$ matrix. Hardness decreased because of a lower hardness value of Mo, whereas fracture toughness increased. For $Al_2O_3,\;Mo\;and\;MnO_2$ composite, grain growth was facilitated by MnOB and it showed a lower fracture strength because of grain growth effect with increasing Mo and $MnO_2$ content. Hardness decreased because of the grain growth of matrix and coalesced Mo particles to be located in grain boundary, whereas fracture toughness increased.

• Solar Energy
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• v.11 no.3
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• pp.53-61
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• 1991

In this research, Octacosane($C_{28}H_{58}$) and Sodium Acetate Trihydrate($CH_3COONa{\cdot}3H_2O$) were selected as latent heat storage materials to store off-peak electricity or waste heat of an industrial plant. Experimental analyses were performed in terms of the variation of phase change temperature and latent heat, phase change stability for the long term utilization. The results were as follows. 1. The phase change temperatures of industrial grade Octacosane and Sodium Acetate Trihydrate were $60.7^{\circ}C$ and $57.4^{\circ}C$, the latent heat were 60.6kcal/kg and 51.1kcal/kg respectively. 2. The latent heat quantity of Octacosane was decreased with the increasing number of phase change cycles. It decreased from 60.6kcal/kg to 47.2kcal/kg upto 200 cycles and then no variation was observed after 200 cycles. 3. To prevent the supercooling of Sodium Acetate Trihydrate, the nucleating agent, Sodium Pyrophosphate Decahydrate of 3 wt% was added, and then the supercooling temperature (Tm-Tsc) was decreased from $25.7^{\circ}C$ to $1^{\circ}C$. The phase separation was disappeared by the addition of CMC-Na of 3 wt% as a thickener. It was found that the optimal quantity of nucleating agent and thickener was 4wt% considering the stability of SAT as a latent heat storage material. 4. The phase change temperature of Sodium Acetate Trihydrate($CH_3COONa{\cdot}3H_2O$) was adjusted from 57.4 to $46.2^{\circ}C$ by the addition of UREA. And then the latent heat quantity was decreased from 51.1 to 38.3kcal/kg. 5. When the heat storage capacities between the sensible and latent heat storage materials were analyzed and compared in heating process from 30 to $90^{\circ}C$, the heat storage capacity of Octacosane was 2.45 times larger than water and 12.5 times than granite at $60.7^{\circ}C$, and the heat storage capacity of Sodium Acetate Trihydrate was 2.53 times larger than water and 12.91 times than granite at $57.4^{\circ}C$.

• Journal of the Korean Wood Science and Technology
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• v.35 no.1
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• pp.73-80
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• 2007

This study was carried out to separate the heavy toxic metals in eco-building materials by low-temperature pyrolysis, especially arsenic (As) compounds in CCA wood preservative as a solid in char. The pyrolysis was carried out to heat the CCA-treated Hemlock at $280^{\circ}C$, $300^{\circ}C$, $320^{\circ}C$, and $340^{\circ}C$ for 60 mins. Laboratory scale pyrolyzer composed of [preheater$\rightarrow$pyrolyzer$\rightarrow$1st water scrubber$\rightarrow$2nd bubbling flask with 1% $HNO_3$ solution$\rightarrow$vent], and was operated to absorb the volatile metal compound particulates at the primary water scrubber and the secondary nitric acid bubbling flask with cooling condenser of $4^{\circ}C$ under nitrogen stream of 20 mL/min flow rate. And the contents of copper, chromium and arsenic compounds in its pyrolysis such as carbonized CCA treated wood, 1st washing and 2nd washing liquors as well as its raw materials, were determined using ICP-AES. The results are as follows : 1. The yield of char in low-temperature pyrolysis reached about 50 percentage similar to the result of common pyrolytic process. 2. The higher the pyrolytic temperature was, the more the volatiles of CCA, and in particular, the arsenic compounds were to be further more volatile above $320^{\circ}C$, even though the more repetitive and sequential monitorings were necessary. 3. More than 85 percentage of CCA in CCA-treated wood was left in char in such low-temperature pyrolytic condition at $300^{\circ}C$. 4. Washing system for absorption of volatile CCA in this experiment required much more contacting time between volatile gases and water to prevent the loss of CCA compounds, especially the loss of arsenic compound. 5. Therefore, more complete recovery of CCA components in CCA-treated wood required the lower temperature than $320^{\circ}C$, and the longer contacting time of volatile gases and water needed the special washing and recovery system to separate the toxic and volatile arsenic compounds in vent gases.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.3 s.32
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• pp.23-30
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• 2004

Interfacial reaction of Pb-free $Sn0.7wt{\%}Cu$ and $Sn3.8wt{\%}Ag0.7wt{\%}Cu$ solders and Pt during aging has been investigated. After the $Sn3.8wt{\%}Ag0.7wt{\%}Cu/Pt$ specimens were reflowed at $250^{\circ}C$ for 30s and the $Sn0.7wt{\%}Cu/Pt$ specimens were reflowed at $260^{\circ}C$, the specimens were aged at $125^{\circ}C,\;150^{\circ}C$ and $170^{\circ}C$ for 25-121 hours. The intermetallic thitkness and morphology change during aging were characterized using SEM, EDS and XRD. $PtSn_4$ and $PtSn_2$ were observed in the solder/pt interface and the intermetallic formation was governed by diffusion. The activation energy of intermetallic formation was 145.3 kJ/mol for$Sn3.8wt{\%}Ag0.7wt{\%}Cu/Pt$ specimens for $Sn0.7wt{\%}Cu/Pt$ specimens from the measurement of the intermetallic thickness with aging temperature and time.

• Economic and Environmental Geology
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• v.39 no.3 s.178
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• pp.285-299
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• 2006

The Mireuksaji stone pagoda in Iksan is the largest stone pagoda existing in Eastern Asia. It was assumed that originally it had been established in the shape of nine-storied pagoda but as time went by only six-storied pagoda remained partially due to collapsing, repair and reconstruction. According to the reference, we can't make sure when its modification happened. The form that the pagoda is having now, was modified with concrete by the Japanese during the 1910s. The materials mixed in concrete were mixture of Portland cement, all sorts of stone, sand, and a little bit of new building stone, additive and compound. And also these materials were applied to cultural assets without any experiment at the time of 1910s as maintenance, which are still used recently. To prevent the change of its shape, the west side, south side and the north side which is partially destructed was rebuilt and reinforced with concrete and some of the deformed parts were also filled. The amounts of concrete used were about 200 tons. Such method had prevented the pagoda from destructing, however, by choosing a wrong repair method, its surface of the stone has secondary contaminants and precipitation caused by concrete. This kind of contamination speeds up the weathering which accelerates the aging mechanism of the stone to make it even harder to revive the absence of historical nature. Therefore, we are to find the best cleaning method to remove the secondary hazard contaminants.