환경인자에 노출된 탄소섬유/에폭시 복합재의 장기 층간전단강도 예측

윤성호 ( Sung Ho Yoon ),( Ya Long Shi ) 한국복합재료학회 2017 Composites research Vol.30 No.1

본 연구에서는 환경인자에 노출된 탄소섬유/에폭시 복합재의 층간전단강도를 이용하여 장기 성능을 예측하였다. 필라멘트와인딩 공법으로 제작된 층간전단시편은 분위기 온도가 50℃, 70℃, 100℃인 건조 조건과 분위기 온도가 25℃, 50℃, 70℃인 침수 조건에 각각 3000시간까지 노출시켰다. 연구결과에 따르면 분위기 온도가 50℃ 와 70℃인 건조 상태에서는 층간전단강도가 노출시간에 따라 크게 변하지 않지만 분위기 온도가 100℃인 건조 상태에서는 노출시간이 길어지면 후경화로 인해 다소 증가한다. 그러나 분위기 온도가 25℃인 침수 상태의 경우 층간전단강도는 노출 초기에 크게 변하지 않다가 노출시간이 길어지면 감소하고 감소 정도는 분위기 온도가 높아지면 커진다. 각 분위기 온도에 대한 층간전단강도 선형회귀식은 침수 상태에 3000시간까지 노출된 시편에서 얻은 층간전단강도에서 구할 수 있었다. 이들 선형 회귀식을 이용하면 층간전단강도는 분위기 온도가 25℃와 50℃인 경우 측정값의 5.5% 이내, 분위기 온도가 70℃인 경우 측정값의 2.3% 이내로 예측이 가능하였다. 따라서 제시된 성능 예측 절차는 환경인자에 노출된 탄소섬유/에폭시 복합재의 장기 층간전단강도를 잘 예측할 수 있다. The purpose of this study was to predict the long-term performance using the interlaminar shear strength of carbon fiber/epoxy composites exposed to environmental factors. Interlaminar shear specimens, manufactured by the filament winding method, were exposed to the conditions of drying at 50℃, 70℃, and 100℃ and of immersion at 25℃, 50℃, and 70℃ for up to 3000 hours, respectively. According to the results, the interlaminar shear strength did not vary significantly with the exposure time for the drying at 50℃ and 70℃, but it increased somewhat for the drying at 100℃ due to the post curing as the exposure time increased. The interlaminar shear strength of the specimens exposed to the immersion at 25℃ did not change significantly at the beginning of exposure, but it decreased with the exposure time and the degree of decrease increased as the environmental temperature increased. The linear regression equations for the environmental temperatures were obtained from the interlaminar shear strength of the specimens exposed to the immersion for up to 3000 hours. Using these linear regression equations, the interlaminar shear strength was estimated to be within 5.5% of the measured value at 25℃ and 50℃, and 2.3% of the measured value at 70℃. Therefore, the proposed performance prediction procedures can predict well the long-term interlaminar shear strength of carbon fiber/epoxy composites exposed to environmental factors.

Cloning and Overexpression of a Paenibacillus β-Glucanase in Pichia pastoris: Purification and Characterization of the Recombinant Enzyme

( Pei Long Yang ),( Peng Jun Shi ),( Ya Ru Wang ),( Ying Guo Bai ),( Kun Meng ),( Hui Ying Luo ),( Tie Zheng Yuan ),( Bin Yao ) 한국미생물생명공학회 2007 Journal of microbiology and biotechnology Vol.17 No.1

Grubbs` Catalyst의 열안정성 및 자가치료제와의 반응성 평가

윤성호 ( Sung Ho Yoon ),( Ya Long Shi ),( Jun Feng ),장세용 ( Se Yong Jang ) 한국복합재료학회 2015 Composites research Vol.28 No.6

본 연구에서는 자가손상보수에 적용되는 Grubbs’ catalyst의 열안정성과 자가치료제와의 반응성을 조사하였다. 이를 위해 제조사에서 공급된 4종류를 고려하였으며 제조사에서 공급받은 상태와 기계적으로 분쇄시킨 상태로 시험하였다. 자가치료제는 Dicyclopentadiene (DCPD)과 5-ethylidene-2-norbonene (ENB)을 적절한 비율로 혼합한 4종류를 고려하였다. 촉매의 열안정성을 조사하기 위해 시차주사 열량측정장치를 통해 온도에 따른 열흐름변화를 측정하였다. 자가치료제와의 반응성을 평가하기 위해 촉매와 혼합된 자가치료제의 반응열을 측정하였다. 이때 촉매는 자가치료제와 반응할 때의 최대온도와 최대온도 도달시간을 고려하여 Fluka Chemika Grubbs’ catalyst를 적용하였다. 연구결과에 따르면 촉매는 제조사에 따라 다른 형상을 나타내며 입자의 크기가 작은 촉매가 자가 치료제와 높은 반응성을 나타내었다. ENB의 혼합비가 높은 자가치료제가 촉매와 혼합되면 최대온도는 증가하고 최대온도 도달시간은 빨라졌다. 또한 촉매의 양이 많을수록 최대온도는 높아지고 최대온도 도달시간은 빨라졌다. 촉매의 열안정성과 자가치료제와의 반응성을 고려할 때 0.5 wt% 촉매와 D3E1 자가치료제가 자가손상보수를 위한 최적 조건임을 알 수 있었다. 마지막으로 노출된 분위기 온도에 따라 촉매에 열분해가 발생할 수 있기 때문에 촉매가 열안정성을 갖는 온도보다 높은 온도에 노출되지 않도록 하여야 한다. This study investigated the thermal stability of Grubbs’ catalyst and its reactivity with self-healing agents for self-healing damage repair. Four types of Grubbs’ catalyst supplied by manufacturers were considered and each catalyst was tested in as-received and grinded conditions. Four types of self-healing agents were prepared by varying the mixing ratio of dicyclopentadiene (DCPD) and 5-ethylidene-2-norbonene (ENB). Heat flows as a function of temperature were measured through a differential scanning calorimetry (DSC) to determine the thermal stability of catalysts. Reaction heats of self-healing agents with the catalyst were measured to evaluate the reactivity of the catalyst. For this evaluation, Fluka Chemika Grubbs’ catalyst was used based on the maximum temperature and the time to reach the maximum temperature. According to the results, catalysts had different shapes depending on the manufacturer and the results showed that the smaller the size of the catalyst the higher the reactivity with self-healing agents. As the ENB ratio in self-healing agents increased, the maximum temperature increased, and the time to reach the maximum temperature decreased. As the amount of the catalyst increased, the maximum temperature increased, and the time to reach the maximum temperature decreased. Considering the thermal stability of the catalyst and its reactivity with the self-healing agent, combination of 0.5 wt% catalyst and the D3E1 self-healing agent was optimal for self-healing damage repair. Finally, as the thermal decomposition may occur depending on the environmental temperature, the catalyst must not be exposed to temperature higher than that is necessary to maintain the thermal stability of the catalyst.

Carboxymethyl Flavonoids and A Monoterpene Glucoside from Selaginella moellendorffii

Hong-Sheng Wang,Ling Sun,Yue-Hu Wang,Ya-Na Shi,Gui-Hua Tang,Fu-Wei Zhao,Hong-Mei Niu,Chun-Lin Long,Ling Li 대한약학회 2011 Archives of Pharmacal Research Vol.34 No.8

A new dihydroflavone, 5-carboxymethyl-7,4'-dihydroxyflavonone (1), and its glucoside 5-carboxymethyl-7,4'-dihydroxyflavonone-7-O-β-D-glucopyranoside (2), and one new monoterpene glucoside, (4Z,6E)-2,7-dimethyl-8-hydroxyocta-4,6-dienoic acid 8-O-β-D-glucopyranoside (3), were isolated from the whole plants of Selaginella moellendorffii. Their structures were determined by spectroscopic methods and chemical transformation. Compound 2 was evaluated for the ability to enhance glucose consumption in normal and insulin-resistant L6 muscle cells induced by high concentrations of insulin and glucose. Glucose consumption in insulin-resistant cells (but not in normal cells) was increased 15.2 ± 3.3% (p < 0.01) by compound 2 at a concentration of 0.1 μM in the presence of insulin (1 nM).

Clinical Study of Thalidomide Combined with Dexamethasone for the Treatment of Elderly Patients with Newly Diagnosed Multiple Myeloma

Chen, Hai-Fei,Li, Zheng-Yang,Tang, Jie-Qing,Shen, Hong-Shi,Cui, Qing-Ya,Ren, Yong-Ya,Qin, Long-Mei,Jin, Ling-Juan,Zhu, Jing-Jing,Wang, Jing,Ding, Jie,Wang, Ke-Yuan,Yu, Zi-Qiang,Wang, Zhao-Yue,Wu, Tian Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.9

Objective: To investigate the relationship between the efficacy and safety of different doses of thalidomide (Thal) plus dexamethasone (Dex) as the initial therapy in elderly patients with newly diagnosed multiple myeloma (MM). Methods: Clinical data of 28 elderly patients with newly diagnosed MM who underwent the TD regimen as the initial therapy were analyzed retrospectively. The patients were divided into two groups according to the maximal sustained dose of Thal: lower dose (group A) and higher dose (group B). The overall response rate (ORR), progression free survival (PFS), overall survival (OS), and adverse events (AES) were compared between the two groups. Results: A total of 28 patients were followed up with a median of 18 months. The ORR was 60.1%. The median response time and PFS were 2.0 and 17.0 months, respectively. The mean sustained dose of Thal in group B was significantly higher than group A (292.9 mg v 180.4 mg, P=0.01). There was no significantly difference in ORR (57.1% v 64.3%, P=1.00) and PFS (9.63months v 17.66 months, P=0.73) between groups A and B. During the follow up, only five patients died (<40%) and, therefore, median OS values were not available. It is estimated, however, that the mean survival time in the two groups was 35.6 and 33.4 months (P>0.05), respectively. All of the patients tolerated the treatment well. The incidence of AES in patients with a grading above 3 in group B was significantly higher than in group A (P=0.033). Conclusions: The TD regimen results in a high response rate and manageable AES as the initial therapy in elderly patients with MM. TD should be considered as the front line regimen for the treatment of elderly patients with MM in areas with financial constraints. The clinical response can be achieved at a low dose Thal with minimal toxicity.

Rapid and Sensitive Detection of Salmonella in Chickens Using Loop-Mediated Isothermal Amplification Combined with a Lateral Flow Dipstick

( Zhi-ke Liu ),( Qiu-yu Zhang ),( Ning-ning Yang ),( Ming-guo Xu ),( Jin-feng Xu ),( Ming-long Jing ),( Wen-xing Wu ),( Ya-dong Lu ),( Feng Shi ),( Chuang-fu Chen ) 한국미생물생명공학회(구 한국산업미생물학회) 2019 Journal of microbiology and biotechnology Vol.29 No.3

Salmonellosis is a highly contagious bacterial disease that threatens both human and poultry health. Tests that can detect Salmonella in the field are urgently required to facilitate disease control and for epidemiological investigations. Here, we combined loop-mediated isothermal amplification (LAMP) with a chromatographic lateral flow dipstick (LFD) to rapidly and accurately detect Salmonella. LAMP primers were designed to target the Salmonella invA gene. LAMP conditions were optimized by adjusting the ratio of inner to outer primers, MgSO₄ concentration, dNTP mix concentration, amplification temperature, and amplification time. We evaluated the specificity of our novel LAMP-LFD method using six Salmonella species and six related non-Salmonella strains. All six of the Salmonella strains, but none of the non-Salmonella strains, were amplified. LAMP-LFD was sensitive enough to detect concentrations of Salmonella enterica subsp. enterica serovar Pullorum genomic DNA as low as 89 fg/μl, which is 1,000 times more sensitive than conventional PCR. When artificially contaminated feed samples were analyzed, LAMP-LFD was also more sensitive than PCR. Finally, LAMP-LFD gave no false positives across 350 chicken anal swabs. Therefore, our novel LAMP-LFD assay was highly sensitive, specific, convenient, and fast, making it a valuable tool for the early diagnosis and monitoring of Salmonella infection in chickens.