• Elastomers and Composites
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• 제55권4호
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• pp.306-313
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• 2020

To investigate the reinforcing effects of functional fillers in nitrile rubber (NBR) materials, high-structure carbon black (HS45), coated calcium carbonate (C-CaCO3), silica (200MP), and multi-walled carbon nanotubes (MWCNTs) were used as functional filler, and carbon black (SRF) as a common filler were used for oil-resistant rubber. The curing and mechanical properties of HS45-, 200MP-, and MWCNT-filled NBR compounds were improved compared to those of the SRF-filled NBR compound. The reinforcing effect also increased with a decrease in the particle size of the fillers. The C-CaCO3-filled NBR compound exhibited no reinforcing effect with increasing filler concentration because of their large primary particle size (2 ㎛). The reinforcing behavior based on 100% modulus of the functional filler based NBR compounds was compared by using several predictive equation models. The reinforcing behavior of the C-CaCO3-filled NBR compound was in accordance with the Smallwood-Einstein equation whereas the 200MP- and MWCNT-filled NBR compounds fitted well with the modified Guth-Gold (m-Guth-Gold) equation. The SRF- and HS45-filled NBR compounds exhibited reinforcing behavior in accordance with the Guth-Gold and m-Guth-Gold equations, respectively, at a low filler content. However, the values of reinforcement parameter (100Mf/100Mu) of the SRF- and HS45-filled NBR compounds were higher than those determined by the predictive equation model at a high filler content. Because the chains of SRF composed of spherical filler particles are similarly changed to rod-like filler particles embedded in a rubber matrix and the reinforcement parameter rapidly increased with a high content of HS45, the higher-structured filler. The reinforcing effectiveness of the functional fillers was numerically evaluated on the basis of the effectiveness index (��SRF/��f) determined by the ratio of the volume fraction of the functional filler (��f) to that of the SRF filler (��SRF) at three unit of reinforcing parameter (100Mf/100Mu). On the basis of their effectiveness index, MWCNT-, 200MP-, and HS45-filled compounds showed higher reinforcing effectiveness of 420%, 70%, and 20% than that of SRF-filled compound, respectively whereas C-CaCO3-filled compound exhibited lower reinforcing effectiveness of -50% than that of SRF-filled compound.

• Nutrition Research and Practice
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• 제15권3호
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• pp.367-381
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• 2021

BACKGROUND/OBJECTIVES: This study aimed to establish a mother and child cohort in the Chinese population, and investigate human breastmilk (HBM) composition and its relationship with maternal body mass index (BMI) and infant growth during the first 3 mon of life. SUBJECTS/METHODS: A total of 101 Chinese mother and infant pairs were included in this prospective cohort. Alterations in the milk macronutrients of Chinese mothers at 1 mon (T1), 2 mon (T2), and 3 mon (T3) lactation were analyzed. HBM fatty acid (FA) profiles were measured by gas chromatography (GC), and HBM proteomic profiling was achieved by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). RESULTS: During the first 3 mon of lactation (P < 0.05), significant decreases were determined in the levels of total energy, fat, protein, and osteopontin (OPN), as well as ratios of long-chain saturated FA (including C16:0, C22:0 and C24:0), monounsaturated FA (including C16:1), and n-6 poly unsaturated FA (PUFA) (including C20:3n-6 and C20:4n-6, and n-6/n-3). Conversely, butyrate, C6:0 and n-3 PUFA C18:3n-3 (α-linolenic acid, ALA) were significantly increased during the first 3 mon (P < 0.05). HBM proteomic analyses distinguished compositional protein differences over time (P = 0.001). Personalized motherinfant analyses demonstrated that HBM from high BMI mothers presented increased total energy, fat, protein and OPN, and increased content of n-6 PUFA (including C18:3n-6, C20:3n-6 and n-6/n-3 ratio) as compared with low BMI mothers (P < 0.05). Furthermore, BMI of the mothers positively correlated with the head circumference (HC) of infants as well as the specific n-6 PUFA C20:3n-6 over the 3 time points examined. Infant HC was negatively associated with C18:0. CONCLUSION: This study provides additional evidence to the Chinese HBM database, and further knowledge of FA function. It also helps to establish future maternal strategies that support the healthy growth and development of Chinese infants.

• 한국식품과학회지
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• 제53권1호
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• pp.1-11
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• 2021

본 논문에서는 최근 10년간(2010-2019년) 바이러스에 의한 식중독 통계 및 바이러스 검출법과 제어법에 대한 자료를 정리하여 나타냈다. 국내에서 지난 10년 동안 바이러스에 의해 발생한 식중독 사고 488건 중 94.9%가 노로바이러스에 의한 것으로 확인되어 노로바이러스가 국내에서 가장 주요한 식중독 바이러스로 생각된다. 노로바이러스를 검출하는 방법으로는 PCR을 이용한 방법이 주로 보고되고 있으며 현재(2020년 12월) 식품 공전에 등록된 방법(고시 제 2010-45호)에 따라 전기 영동을 기반으로 한 one-step RT PCR 및 semi-nested PCR 방법이 널리 이용되고 있다. 또한 최근 DNA sequencing 기술이 발달됨에 따라서 검출된 바이러스의 서열을 분석하여 이미 보고된 바이러스의 서열과 비교한 논문들이 많이 보고되었다. 이 외에도 real-time PCR을 적용한 논문들도 보고되고 있으며 앞으로는 전기 영동을 실시하는 conventional PCR을 대신하여 신속하게 정량 검출이 가능한 realtime PCR의 활용이 늘어날 것으로 생각한다. 기타 바이러스의 검출에 있어서도 역시 PCR을 활용한 방법이 주로 보고되고 있으며 multiplex PCR을 활용하여 여러 종류의 바이러스를 동시에 검출하고자 하는 노력이 이루어지고 있다. 더 나아가서, 자기 면역력 분리와 퀀텀닷 분석 방법 등을 이용한 신속 검출법이 제시되고 있어 앞으로 여러 식품에 오염된 바이러스를 현장에서 신속분리 및 검출하는데 이용할 수 있을 것으로 전망된다. 한편, 노로바이러스는 실험실에서 배양하기가 어렵기 때문에 노로바이러스 제어 연구는 대체재를 이용한 방법들이 주를 이루었다. 옴 가열을 포함한 여러 종류의 열처리와 초고압, 오존, 감마선, 광펄스 등의 비가열 처리를 이용하여 노로바이러스의 저감 정도를 살펴본 연구들이 최근 보고되었다. 일반적으로 물이나 완충용액보다는 식품 샘플에서 바이러스의 저감 정도가 낮게 관찰되었는데 식품 matrix가 이러한 물리적 처리에 간섭 효과를 나타내기 때문으로 생각되며 이를 극복하기 위해서는 여러 물리적, 화학적 처리를 조합하여 처리할 필요가 있다. 기타 바이러스 제어 연구에 있어서는 열, 광펄스, 고압력 등의 물리적 처리와 더불어 살균제(sanitizer)를 적용한 논문들이 보고되고 있으며 식중독 바이러스의 저감 메커니즘에 대한 체계적인 연구가 수행되고 있는 것을 확인하였다. 여러 물리적, 화학적 처리에 대해서 식중독 바이러스가 저항성을 갖는 이유와 사멸되는 메커니즘을 정확하게 이해한다면 추후 여러 식품에서의 바이러스에 대한 안전성을 확보하는데 도움이 될 것으로 사료된다.

• 한국응용과학기술학회지
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• 제38권1호
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• pp.19-28
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• 2021

부식은 환경과의 반응에 의한 금속의 열화이다. 이는 완전히 제거하기가 어렵다. 부식은 보호장벽이 파괴 된 후 빠르게 진행되며 매트릭스로의 금속 양이온 확산, 산화물 형성과 국소 pH 변화 같은 금속 표면과 국소 환경의 조성과 특성을 변경하는 여러 반응이 일어난다. 강과 철의 부식에 대한 연구는 이론적, 실제적 관심사이며 상당한 관심을 받고 있다. 산업용 산세척, 산 스케일 제거, 세척 및 유정 산성화에 널리 사용되는 산 용액은 금속 재료에 대한 부식 공격을 억제하기 위해 부식 억제제를 사용해야한다. 녹을 물리적으로 제거하려면 고가의 특수 장비가 필요하며 이를 화학적으로 제거하면 부식을 유발하거나 금속의 수명을 단축 할 수 있다. 본 연구에서는 퍼머 환원제와 킬레이트 개념을 적용하여 화장품 및 식품소재를 이용한 친환경 녹 세정제를 개발하였고 산업 및 온수 관, 각종 산업 기기의 녹을 제거하기 위해 적용하여 보았다. 그 결과, 녹 세정제는 기존 처리 방식에 비해 녹을 더 효과적이고 안전하게 제거하는 것으로 나타났다. 동일한 시간에서 녹 제거 효율은 기존의 방법보다 공업용 배관의 경우 1.75 ~ 2.5 배, 보일러 온수용 배관의 경우 1.56 ~ 2.2 배 우수하였다.

• Computers and Concrete
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• 제31권3호
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• pp.267-276
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• 2023

The main purpose of the current research is to develop an efficient two variables trigonometric shear deformation beam theory to investigate the buckling behavior of symmetric and non-symmetric functionally graded carbon nanotubes reinforced composite (FG-CNTRC) beam resting on an elastic foundation with various boundary conditions. The proposed theory obviates the use to shear correction factors as it satisfies the parabolic variation of through-thickness shear stress distribution. The composite beam is made of a polymeric matrix reinforced by aligned and distributed single-walled carbon nanotubes (SWCNTs) with different patterns of reinforcement. The material properties of the FG-CNTRC beam are estimated by using the rule of mixture. The governing equilibrium equations are solved by using new analytical solutions based on the Galerkin method. The robustness and accuracy of the proposed analytical model are demonstrated by comparing its results with those available by other researchers in the existing literature. Moreover, a comprehensive parametric study is presented and discussed in detail to show the effects of CNTs volume fraction, distribution patterns of CNTs, boundary conditions, length-to-thickness ratio, and spring constant factors on the buckling response of FG-CNTRC beam. Some new referential results are reported for the first time, which will serve as a benchmark for future research.

• 지질공학
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• 제33권3호
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• pp.427-438
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• 2023

본 연구에서는 다양한 암종이 분포하는 단양 지질공원 내에서 발생한 산사태를 대상으로 야외지질조사를 통해 유형을 분류하고, 샘플링 및 실내 시험을 통해 산사태 구성 물질의 역학적‧수리학적 특성을 분석하였다. 토석류 산사태 유형은 석회암 및 대리암, 셰일, 반상변정질 편마암 지역에서 발생하였으며, 석회암 및 대리암 지역에서는 카렌지형의 영향을 받아 암반과 암반 사이의 토사가 붕괴되는 형태로 다른 두 지역의 산사태와 구분된다. 토질시험 결과에서는 조립질 함량이 많은 편마암 풍화토가 다른 두 지역의 풍화토에 비해 내부마찰각이 높고 점착력이 작으며 투수계수가 큰 특징을 보인다. 암반 산사태 유형은 천매암, 사암, 역암 지역에서 발생하였으며, 천매암 지역에서는 평면파괴 형태가, 사암 지역에서는 부석형 낙석 형태가, 역암 지역에서는 전석형 낙석 형태가 발달하고 있다. 천매암의 전단강도는 동일한 암질의 타 암종에 비해 훨씬 낮게 나타나며, 역암의 슬레이크 내구성 지수는 타 암종과 유사하나 시험 전‧후 시료의 상태를 비교하면 기질부의 차별풍화 및 이로 인한 역의 탈락 형태가 뚜렷이 관찰된다. 본 연구의 결과는 지질특성별 산사태 유형에 따른 적절한 보강방안 및 방재대책을 수립하는데 기여할 수 있을 것으로 기대된다.

• 대한본초학회지
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• 제24권3호
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• pp.161-167
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• 2009

Objectives : Maekmoondong-tang (MMDT), a Korean herbal medicine, has been used to treat severe dry cough in patients with bronchitis and pharyngitis. MMDT has been reported to have anti-inflammatory, anti-allergic, immunomodulatory, secretory-modulating, and metabolic regulatory actions. However, there are no evidence in regard to the effects of MMDT on carcinogenesis and metastasis. Here, we investigated the effects of 70% ethanol extract of MMDT on cell viability, apoptosis, and motility in human hepatocarcinoma HepG2 cells. Methods : Cell viability was measured using the CCK-8 assay, and the apoptosis induction was evaluated by caspase-3 activity. To detect apoptotic features, the cells treated with MMDT were stained with 4'-6-diamidino-2-phenylindole (DAPI). Cell motility was examined by Boyden chamber assay and Real-time Cell Index of Migration assay. Gelatin zymography also performed to measure matrix metalloproteinase (MMP)-2/9 activity. Results : We found that MMDT significantly inhibited cell proliferation and increased caspase-3 activity in a dose-dependent manner in HepG2 cells. Apoptotic features such as chromatin condensation and apoptotic bodies were observed in MMDT-treated cells by DAPI staining. MMDT also suppressed PMA-induced cell motility and activities of MMP-2/9. Conclusions : Our results exhibited that MMDT possess the anti-carcinogenetic and anti-metastatic activities via caspase-3 activation and down-regulation of cell motility and invasion in HepG2 cells. Therefore, these findings suggest that MMDT could be potentially applied to the prevention and treatment of cancer.

• 한국환경농학회지
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• 제42권1호
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• pp.71-81
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• 2023

An accurate and easy-to-use analytical method for determining isocycloseram and its metabolites (SYN549431 and SYN548569) residue is necessary in various food matrixes. Additionally, this method should satisfy domestic and international guidelines (Ministry of Food and Drug Safety and Codex Alimentarius Commission CAC/GL 40). Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) was used to determine the isocycloseram and its metabolites residue in foods. To determine the residue and its metabolites, a sample was extracted with 20 mL of 0.1% formic acid in acetonitrile, 4 g magnesium sulfate anhydrous and 1 g sodium chloride and centrifuged (4,700 G, 10 min, 4℃). To remove the interferences and moisture, d-SPE cartridge was performed before LC-MS/MS analysis with C₁₈ column. To verify the method, a total of five agricultural commodities (hulled rice, potato, soybean, mandarin, and red pepper) were used as a representative group. The matrix-matched calibration curves were confirmed with coefficients of determination (R²) ≥ 0.99 at a calibration range of 0.001-0.05 mg/kg. The limits of detection and quantification were 0.003 and 0.01 mg/kg, respectively. Mean average recoveries were 71.5-109.8% and precision was less than 10% for all five samples. In addition, inter-laboratory validation testing revealed that average recovery was 75.4-107.0% and the coefficient of variation (CV) was below 19.4%. The method is suitable for MFDS, CODEX, and EU guideline for residue analysis. Thus, this method can be useful for determining the residue in various food matrixes in routine analysis.

• 센서학회지
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• 제33권1호
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• pp.34-39
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• 2024

Energy harvesting technology that converts the wasted energy resources into electrical energy is emerging as a semipermanent power source for self-powered electronics and wireless low-power sensor systems. Among the various energy conversion techniques, flexible piezoelectric energy harvesters (f-PEHs), using materials with piezoelectric effects, have attracted significant interest because they can harvest a small mechanical energy into electrical signals without constraints of time and space in various environments. In this study, we used a flexible piezoelectric composite film fabricated by dispersing BaHf_xTi_(1-x)O₃ (x = 0, 0.01, 0.05, 0.1) piezoelectric powders inside a polymeric matrix to facilitate f-PEHs. The fabricated f-PEH with optimal Hf contents (x = 0.05) generated a maximum output voltage of 0.95 V and current signal of 130 nA with stable electrical/mechanical disabilities under periodically bending deformations. In addition, we demonstrated a cantilever-type f-PEH and investigated its potential as a sensor by characterizing the output performance under mechanical vibrations at various frequencies. This study provides the breakthrough for realizing self-powered energy harvesting and sensing systems by adopting the lead-free piezoelectric composites under vibrational environments.

• Journal of Acupuncture Research
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• 제24권6호
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• pp.1-14
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• 2007

Backgrounds : Rheumatoid Arthritis(RA) is known as the chronic inflammatory diseasethat induces persistent inflammation in the joint cavity. The destruction of cartilage occurs as the result of bones destoyed by pannus, several influential cytokines induced by the synovial capsulitis, varieties of proteinases, $O_2$ radicals, and the secondary degenerative changes of articular cartilage. The type 2 collagen-induced arthritis model is used in recent experimental research on rheumatoid arthritis. Cervus elaphus sibiricus (Nockyong) has the effect of relieving pain by nourishing the muscles, joints, and bones. It is also known to be efficacious in promoting and enhancing the immune system. The objective of this study was to investigate the effect of Cervus elaphus sibiricus herbal acupuncture to inhibit the generation of proinflammatory enzyme on type 2 collagen-induced arthritis. I investigated the inhibition of mRNA transcription of MIF(macrophage migration inhibitory factor), $TNF-{\alpha}$(Tumor necrosis $factor-{\alpha}$) and MMP-9 (matrix metalloproteinase-9) of Cervus elaphus sibiricus herbal acupuncture using an in vitro test. Also investigated was the inhibition of differentiation of Th 1 cells and activation of cytokines(MIF, $TNF-{\alpha}$, IL-6, MMP-9), which are known to cause initial RA ,and are also related to the morphology of the synovial membranes of the joint capsule, by an in vivo test, using CIA(collagen induced arthritis) model mice. Materials & methods : The laboratory animals used in this experiment were 4 week-old DBA female mice, weighing approximately 20 grams, and adjusted to the laboratory environment. The experiment was divided into the normal group(NOR)-no treated group, control group(CON)-CIA induced group, and sample group(SAM)-Cervus elaphus sibiricus herbal acupuncture treated group. RA was induced in the mice via injection of $50{\mu}{\ell}$ C II mixed CFA. The Cervus elaphus sibiricus herbal acupuncture solution was applied on $GB_{35}$(陽陵泉) for 26 days from the 3rd day of RA inducement. The concentration of the solution was determined via a MTT assay. To research the effect on the expression of MIF, $TNF-{\alpha}$ and MMP-9 mRNA, RT-PCR was performed on synovial membrane cells from the knee joint of CIA mice. C II induced RA knee joint's histo-chemical synovial membrane was observed using a specimen model via the Hematoxilin and Eosin dying technique. Results : The expression of mRNA of RA-related cytokines such as MIF, $TNF-{\alpha}$, and MMP-9 dosedependently decreased in the cell from the synovial membranes of the joint, which is treated with Cervus elaphus sibiricus herbal acupuncture solution. In mice treated with Cervus elaphus sibiricusherbal acupuncture, the damage of synovial membranes of the joint was lessened, and differentiation of Th 1 cells was suppressed. The activation of RA-related cytokines such as MIF was suppressed, and the generation of $TNF-{\alpha}$ and MMP-9 showed a statistically significant decreas. Conclusions : It is speculated that Cervus elaphus sibiricus herbal acupuncture has the therapeutic effect of palliating the damage of the tissue impaired by RA by inhibition of the initial RA progression and by regulating excessive differentiation of Th 1 cell as it suppresses the generation of RA-related cytokines during the highest stage of RA by acting on pro-inflammatory enzymes.