• Restorative Dentistry and Endodontics
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• 제29권3호
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• pp.249-266
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• 2004

The purpose of this study was to determine whether pH and time has any influence on the degradation behavior of composite restoration by analyzing the leached monomers of dental composites qualitatively and quantitatively after storage in acetate buffer solution as a function of time using high performance liquid chromatography (HPLC) / mass spectrometer. Materials and Methods：Three commercial composite restorative resin materials (Z-250, Heliomolar and Aeliteflo) with different matrix structure and filler composition were studied. Thirty specimens (7mm $diameter{\times}2mm$ thick) of each material were prepared. The cured materials were stored in acetate buffer solution at different pH (4, 7) for 1, 7 and 45days. As a reference, samples of unpolymerized composite materials of each product were treated with methanol (10mg/ml). Identification of the various compounds was achieved by comparison of their mass spectra with those of reference compound, with literature data. and by their fragmentation patterns. Data were analysed statistically using ANOVA and Duncan's test. Results：1. Amounts of leached TEGDMA in Aeliteflo were significantly larger than those of UDMA in Z-250 and Heliomolar at experimental conditions of different storage time and pH variation (p<0.001). 2. As to comparison of the amounts of leached monomers per sorage time, amounts of leached TEGDMA in Aeliteflo and UDMA in Z-250 and Heliomolar were increased in the pH 4 solution more significantly than in the pH 7 solution after 1day, 7days and 45days, respectively (p<0.001). 3. In total amounts of all the leached monomers with storage times, the overall amounts of pH 4 extracts were larger than those of pH 7 extracts for all resin groups, but there was no significant difference (p>0.05).

• International Journal of Industrial Entomology and Biomaterials
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• 제45권2호
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• pp.93-98
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• 2022

To assess the feasibility of silk sericin for non-textile application, the storage stability and biological safety of sericin were examined. It was extracted at 37℃, 70℃, 100℃, and 121℃ for 1, 3, and 5 h to elucidate the effect of extraction condition on the stability and safety of silk sericin. The solubility was increased till approximately 26% with extraction temperature of 121℃ for 1 h. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that the molecular weight distribution depended on the extraction conditions. Extracted sericin displayed typical UV absorption bands upon spectrometric analysis. To examine the reproducibility of its obtained conformation, sericin was extracted thrice and its circular dichroism (CD) spectra was measured each time. Most CD spectra showed reproducibility regardless of temperature and time except under 100℃ extraction condition. The diversity of CD spectrum showed gradual reduction and was finally coincident with extraction time from 1 to 5 h. Notably, sericin has a negative peak of approximately 200 nm attributed to random coil conformation, regardless of extraction condition. However, at the 100℃ extraction condition, sericin showed both bands to be negative bands of approximately 200 and 220 nm, respectively. Sericin was centrifuged to determine the stability of storage conditions. The sericin extracted at 100℃ and 121℃ for 1 h was found to form gel rapidly within 1 h, but at 121℃ condition, the gel fraction was approximately 20% within 1 h which retained its phase regardless of storage time. The gel fraction of sericin extracted at 100℃ for 5 h increased with time, however at the 121℃ for 5 h condition, the gel fraction was measured to be less than 10% regardless of increase in storage time. Petriflim^TM AC plates test showed that sericin was safe from aerobic bacteria activity by extraction under high temperature.

• 한국식품저장유통학회지
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• 제16권5호
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• pp.636-643
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• 2009

세척 당근에 E. coli O157:H7과 L. monocytogenes를 인위적으로 접종한 후 UV-C 조사 처리에 따른 저장 중 미생물수 변화를 조사하였다. 당근에 접종된 E. coli O157:H7과 L. monocytogenes의 초기 균수가 6-7 log CFU/mL가 되게하였고, 사용된 UV-C 조사선량은 1, 3, 5, $10\;kJ/m^2$이었으며 조사된 시료는 $4{\pm}1^{\circ}C$에서 8일 동안 저장하였다. UV-C 조사는 E. coli O157:H7과 L. monocytogenes의 미생물 수에 있어서 조사선량이 증가할수록 유의적으로(p<0.05) 감소하는 것을 나타냈다. 특히, $10\;kJ/m^2$ 처리구는 대조구와 비교하여 E. coli O157:H7과 L. monocytogenes의 미생물 수를 각각 2.35, 2.38 log CFU/g 감소시켰다. 품질 변화에서는 UV-C 조사 5, $10\;kJ/m^2$ 처리구가 저장 중 당근 표면 $L^*$ value의 급격한 증가와 $a^*$, $b^*$ value의 감소 및 백화현상을 유의적으로(p<0.05) 억제시켰다. 관능적 품질 평가는 5, $10\;kJ/m^2$ 처리구가 대조구에 비해 유의적으로(p<0.05) 높게 나타났다. 따라서 본 연구결과, UV-C 조사 처리는 세척 당근의 저장 중 미생물학적 안전성 확보와 품질유지 향상에 효과적인 것으로 판단된다.

• 한국패류학회지
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• 제26권2호
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• pp.145-149
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• 2010

피조개, Scapharca broughtonii (Schrenck) 정자의 냉장보존을 위해 희석액에 따른 보존효과를 비교하였다. 피조개 정액을 채취하여 600 mM NaCl, Stein solution, 300 mM, 600 mM glucose (10 mM Hepes-pH 7.8), Ringer's solution (230 mM NaCl, 8 mM KCl, 2 mM $CaCl_2$, 3.7 mM $MgCl_2$, 0.2 mM $NaHCO_3$, 10 mM Hepes-pH 7.8), 20%, 25% ASW (NaCl 2.7 g + KCl 0.07 g + $CaCl_2$ 0.12 g + $MgCl_2$ 0.46 g + $NaHCO_3$ 0.05 g + distilled water 100 ml)를 각각 사용하여 $4^{\circ}C$에서 보관하였다. 피조개 정자의 보존효과는 정자의 운동성과 생존율로 평가였다. 피조개 정자는 Ringer's solution에서 7일간 냉장 보전하였을 때 운동성과 생존율을 가장 높았으며, 희석액의 적정 pH는 7.5 이었다.

• 대한금속재료학회지
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• 제49권12호
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• pp.945-949
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• 2011

The cycling characteristics of $MgH_2$ made by hydriding chemical vapor deposition method have been investigated. The particle size of $MgH_2$ made by HCVD was about $1{\mu}m$. The cycling experiment was performed by measuring hydrogen quantity absorbed at 673 K and under 35 atm of hydrogen pressure for 30 min. Up to 3 cycles the hydrogen storage capacity increased, but from 4 to 6 cycles the hydrogen storage capacity decreased rapidly. During this cycling test the particle size increased gradually from $1{\mu}m$ to $6{\mu}m$. This increase was due to sintering by the high reaction temperature and the heat of reaction during hydrogen absorption. From 7 to 30 cycles, the hydrogen storage capacity was maintained at 5.8 wt%. Even after 30 cycles, the plateau pressure was constant.

• 한국식품저장유통학회지
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• 제9권1호
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• pp.51-55
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• 2002

느타리버섯을 이용하여 김치를 제조한 후 숙성 중 식품학적 특성을 조사하였다. 느타리버섯 김치의 숙성기간에 따른 pH를 측정한 결과 생 느타리버섯 김치는 처음에 대조구인 배추김치보다 높았으나, 숙성기간이 지남에 따라 그 값이 배추김치에 비하여 낮게 나타났으며, 데친 느타리버섯 김치는 배추김치보다 조금 높게 나타났고, 적정산도는 pH의 경우와 반대현상으로 나타났다. 아미노태 질소 함량은 숙성기간이 지남에 따라 증가하는 경향이었는데, 생 느타리버섯 김치는 배추김치에 비하여 그 함량이 높게 나타났으며, 데친 느타리버섯 김치는 배추김치와 비슷하게 나타났다. 김치의 환원당은 숙성기간이 지남에 따라 크게 감소하였는데, 생느타리 버섯 김치의 함량은 배추김치보다 높게 나타났고, 데친 느타리버섯 김치는 조금 낮게 나타났다. 배추김치의 생균수는 숙성 2일째는 급격하게 증가하였으며, 그 이후는 거의 비슷한 수로 나타났다. 느타리버섯 김치도 배추김치와 같은 경향이었는데, 그 수는 배추김치보다 약간 낮게 나타났으며, 젖산균수의 경우는 생균수 거의 같은 경향이었다. 상온에서 1일간 저장한 느타리버섯 김치의 관능검사결과 데친 느타리버섯 김치에 비하여 생느타리버섯 김치가 좋은 값을 나타내었으나, 배추김치에 비하여 기호도가 낮게 나타났다.

• 한국발생생물학회지:발생과생식
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• 제7권1호
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• pp.9-13
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• 2003

말똥성게 정자의 냉장보존을 위한 여러 가지 희석액의 보존 효과를 비교하였다. 다양한 농도의 포도당 용액, 인공해수(ASW)를 희석액으로 하여 정자를 4$^{\circ}C$에서 보존하였다 보존효과는 정자 활성지수 (SAI), 생존율 및 말똥성 게 난에 대 한 수정률로 평가하였다. ASW와 1.2 M glucose액을 희석 액으로 하여 30일간 냉장보존하였을 때 가장 높은 운동성 및 생존율을 유지하였다. 정자의 냉장보존을 위한 희석액의 적정 pH는 7.0∼8.0 이었다. 정자의 SAI와 생존율을 높이기 위한 항생제로는 neomycin(400 ppm)이 효과적인 것으로 나타났다

• 한국식품영양과학회지
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• 제19권1호
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• pp.13-20
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• 1990

Yu Ja cheong(Citron product) one of the traditional drinks was processed by a modified method to improve the quality,. Sugar(38%) and sorbitol(12%) were added as partially substi-tuted sugar and experimented about quality stability during storage at 20$\pm$2$^{\circ}C$ comparing with conventional 50% sugar added product. Chemical compositions of the acidity 40. 46mg% total Vitamin and 28.5mg% amino-N and pH was 3.7 During the storage pH reducing sugar and amino-N contents increased slightly while total acididty decreased slightly and reduced vitamin C occupied most part of total vitamin C after proessing was converted to oxidized vitamin C greatly at 70 days of storage. While L a and b values deceased in between modified one and conventional product. e value increased continually during storage {{{{ {C }_{16 { }:_{ } 0 } }}}} {{{{ {C }_{18 { }:_{ }0 } }}}} {{{{ {C}_{18 { }:_{ }1 } }}}} and {{{{ {C }_{18 { }:_{ }2 } }}}} contnts in fatty acid and citric acid itaconic acid malic acid and succinic acid in organic acid were the major componets in both products. Judging from the results of experiments during storage the quality of the modified product was compared quite well with that of vonventional one during storage.

• 한국축산식품학회지
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• 제24권2호
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• pp.121-127
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• 2004

본 연구는 쑥 펠렛 사료를 거세돈과 비거세돈에게 각각 0, 3, 5%를 배합사료에 첨가급여 한 후 도축하여 등심부위를 4$\pm$1$^{\circ}C$에서 보관하면서 저장성을 분석한 결과는 다음과 같다. 돈육의 pH는 시험구에서 거세돈이 대조구에 비하여 약간 낮았지만 비거세돈은 차이가 없었으며, 가열감량과 보수력은 시험구가 대조구에 비하여 약간 높았다. 저장기간 중 돈육의 pH나 가열감량 보수력은 저장기간이 증감함에 모든 처리구에서 증가하였다.(p＜0.05). 육색의 명도(L)는 쑥 펠렛 3%첨가구가 모든 처리구 중에서 가장 높은 값을 나타내었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.254.2-254.2
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• 2014

The Transmission Fourier Transform Infrared spectroscopy (FTIR) of SiOx charge storage layer with the richest silicon content showed an assignment at peaks around 2000~2300 cm-1. It indicated that the existence of many silicon phases and defect sources in the matrix of the SiOx films. The total hysteresis width is the sum of the flat band voltage shift (${\Delta}VFB$) due to electron and hole charging. At the range voltage sweep of ${\pm}15V$, the ${\Delta}VFB$ values increase of 0.57 V, 1.71 V, and 13.56 V with 1/2, 2/1, and 6/1 samples, respectively. When we increase the gas ratio of SiH4/N2O, a lot of defects appeared in charge storage layer, more electrons and holes are charged and the memory window also increases. The best retention are obtained at sample with the ratio SiH4/N2O=6/1 with 82.31% (3.49V) after 103s and 70.75% after 10 years. The high charge storage in 6/1 device could arise from the large amount of silicon phases and defect sources in the storage material with SiOx material. Therefore, in the programming/erasing (P/E) process, the Si-rich SiOx charge-trapping layer with SiH4/N2O gas flow ratio=6/1 easily grasps electrons and holds them, and hence, increases the P/E speed and the memory window. This is very useful for a trapping layer, especially in the low-voltage operation of non-volatile memory devices.