One step bulk modification of poly(L-lactic acid) composites with functional additives to improve mechanical and biological properties for cardiovascular implant applications

Kang, Eun Young,Choi, Bogyu,Park, Wooram,Kim, Ik Hwan,Han, Dong Keun Elsevier 2019 Colloids and Surfaces B Vol.179 No.-

<P><B>Abstract</B></P> <P>Poly(L-lactic acid) (PLLA) has been widely used as a promising biomaterial in biomedical applications due to its biodegradability and high mechanical strength. However, because of the inherent brittleness, low impact resistance, and weak thermal stability of PLLA, the modification process is usually required to utilize it for biomedical devices. Furthermore, acidic byproducts resulting from the hydrolysis of PLLA after implantation reduce the pH of the surrounding environment and cause inflammatory responses in the implanted area, leading to the failure of their clinical applications. To this end, here, we demonstrate a novel modification process for the PLLA composite with various functional additives, such as cis-aconitic anhydride (AA), triacetin (TA), isosorbide derivative (ISB), and/or Pluronic® F127 (F). The modified PLLA composite with TA and F (PLLA/TF) showed significantly improved elongation at break and Young’s modulus and retained tensile strength. Moreover, incorporating magnesium hydroxide (MH) nanoparticles (PLLA/TFMH) significantly reduced acid-induced inflammation responses caused by the acidic degradation products of PLLA. Reduced plasma protein adsorption was observed in the PLLA/TFMH. These results suggest that the one step bulk modification of biodegradable PLLA using TA, F, and MH will have great potential in cardiovascular implant applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Improved mechanical properties of PLLA via one step bulk modification with TA and F. </LI> <LI> Reduced acid-induced inflammation via one step bulk modification of PLLA/TF with MH. </LI> <LI> Increased homogeneity of MH distribution in one step bulk modified PLLA/TFMH. </LI> <LI> Enhanced hemocompatibility of PLLA/TFMH. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

정신분열병에 대한 리스페리돈의 효과 및 안정성

이민수,김용구,김영훈,연병길,오병훈,윤도준,윤진상,이철,정희연,강병조,김광수,김동언,김명정,김상훈,김희철,나철,노승호,민경준,박기창,박두병,백기청,백인호,손봉기,손진욱,양병환,양창국,우행원,이정호,이종범,이홍식,임기영,전태연,정영조,정영철,정인과,정인원,지익성,채정호,한상익,한선호,한진희,서광윤 大韓神經精神醫學會 1998 신경정신의학 Vol.37 No.1

연구목적 : 본 시험의 목적은 임상시험 시작전에 연구자들을 대상으로 PANSS Workshop을 통하여 PANSS, ESRS에 대한 국내에서의 표준화 작업을 구축하고 새로운 정신병 치료제인 리스페리돈의 효과와 안정성을 재확인하여 리스페리돈 사용에 대한 적정화를 이루는데 있다. 연구방법 : 1996년 4월부터 1996년 9월까지 국내 39개 대학병원 정신과에 입원중인 혹은 증상이 악화되어 입원하는 정신분열병 환자 377명을 대상으로 다시설 개방 연구를 시행하였다. 1주일간의 약물 배설기간을 가진후, 리스페리돈을 8주간 투여하였고, 기준점, 1주, 2주, 4주, 그리고 8주후에 평가되었다. 용량은 제1일에는 리스페리돈 1mg씩 1일 2회, 제2일에는 2mg씩 1일 2회, 제3∼7일에는 3mg씩 1일 2회 투여하였다. 이후 환자의 임상상태에 따라 임의로 증량할 수 있으며, 최대 일일 16mg을 초과하지 않도록 하였다. 추체외로 증상을 조절하기 위한 투약을 허용하였다. 임상증상 및 부작용의 평가는 PANSS(Positive and Negative Syndrome Scale), CGI(Clinical Global Impression) 그리고 ESRS(Extrapyramidal Symptom Rating Scale)을 사용하였다. 연구결과 : 377명중 343명(91%)이 8주간의 연구를 완결하였다. 치료 종결시점인 8주후 PANSS 총점수가 20% 이상 호전된 경우를 약물 반응군으로 정의할때, 약물반응군은 81.3%였다. 리스페리돈에 반응하는 예측인자로는 발병연령, 이전의 입원 횟수, 유병기간이 관련 있었다. 리스페리돈은 1주후부터 PANSS양성, 음성, 및 일반정신병리 점수상에 유의한 호전을 보여 효과가 빨랐다. CGI의 경우도 기준점에 비해 1주후부터 유의한 감소를 나타내었다. ESRS의 경우, 파킨슨 평가점수는 기준점과 비교해 투여 1주, 2주, 4주후 유의하게 증가되었다가 8주후 기준점과 차이가 없었다. Dystonia 평가점수는 1주후만 유의한 증가를 보였으며, dyskinesia 평가점수는 유의한 차이가 없었다. 혈압, 맥박수의 생명징후 및 일반 혈액학 검사, 생화학적 검사, 심전도 검사에서 유의한 변화는 없었다. 결 론 : 이상의 다시설 개방 임상 연구를 통해 리스페리돈은 정신분열병 환자에서 양성증상뿐만 아니라 음성증상 및 전반적인 증상에도 효과적인 것으로 사료된다. 보다 명확한 평가를 위해서는 다른 항정신병약물과의 이중맹검 연구가 필요할 것으로 생각되며, 또한 장기적 치료에 대한 평가도 함께 이루어져야 하겠다. Objective : The purpose of this study was to investigate the efficacy and safety of risperidone in the treatment of Korean schizophrenic patients. Method : This multicenter open study included 377 schizophrenic patients drawn from 39 university hospitals. After a wash-out period of 1 week, the schizophrenic patients were treated with risperidone for 8 weeks and evaluated at 5 points ; at baseline, and 1, 2, 4 and 8 weeks of treatment. The dose was increased from 2mg/day(1mg twice daily) to 6mg/day(3mg twice daily) during the first week and adjusted to a maximum of 16mg/day over the next 7 weeks according to the patient's clinical response. Medication to control extrapyramidal symptoms was permitted. The psychiatric and neurological status of the patients was assessed by PANSS, CGI, and ESRS scales. Results : 343(91%) of 377 patients completed the 8-week trial period. Clinical improvement, as defined by a 20% or more reduction in total PANSS score at end point, was shown by 81.3% of patients. The predictors of response to risperidone were associated older age, shorter duration of illness, fewer previous hospitalization. Risperidone had rapid onset of action ; a significant decrease of the total PANSS and three PANSS factor(positive, negative, general), and CGI was already noticed at the end of first week. For the ESRS, parkinsonism rating scores were significantly increased until week 4 comparing with baseline. Dystonia rating scores were significantly increased until week 1, and dyskinesia rating scores were not significantly changed during the study. Laboratory parameters including vital sign, EKG, hematological, and biochemical values showed no significant changes during the trial. Conclusions : This study suggests that risperidone is generally safe and effective against both the positive and negative symptoms in our group of patients.

중 란탄족 산화물의 결합구조와 전기전도성

강영환,최재시,윤기현 연세대학교 대학원 1980 延世論叢 Vol.16 No.2

The electrical conductivity of highly pure polycrystalline Gd₂O₃, Ho₂O₃ and Yb₂O₃ has been measured from 650 to 1050℃ under oxygen pressure range of 10^(-6) to 10² torr. Plots of logσ vs. T at constant oxygen pressure are found to be linear. and the conductivity dependence of oxygen pressure in the high temperature region (750-1050℃) is approximated by σ α po₂1/5.3. This shows that the conduction mechanism is associated with doubly ionized metal vacancies. Fairly low activation energy and the lack of oxygen pressure dependence are found over the temperature range of 650 to 750℃. The conduction mechanism is explained by not metal vacancies, but hopping oxygen ions in the oxides. The sesquioxides exhibit mixed conduction with some ionic conduction and major electronic conduction carriers.

Trioctylamine에 의한 유기산의 추출

강안수,이병철,이한섭,안형환,이영주,류운형 明知大學校 産業技術硏究所 1993 産業技術硏究所論文集 Vol.12 No.-

For elucidation of various parameter's effect on the reactive extraction of organic acidstrioctylamine(TOA)-diluents system, the association model, equilibrium constants and extraction factors(loading) were investigated . The organic acids rosed were propionic. succinic, masonic, and benzoic acid. Extractant was tertiary amine, TOA and diluents were butylaeohol, hexane, and benzene. It was concluded that the loading of monobasic acid of propionic acid were higher than that of dibasic acids of oxalic, and malonic acid with extranctant TOA. In the extraction of monobasic acid the extraction factor was not affected by the initial concentration of extractant amine, but in the extraction of dibasic acids the extraction factor was getting better with decreasing the initial concentration of amine. There was a strong effect of diluents upon the extractien factor, and the order of these factor was as shown below: xylene<Benzene<butylalcohol<choloroform<methylisobutylketone.

식품공장폐수의 활성오니처리중 오존에 의한 산화분해효과

강경수,최영찬,하진환,송대진 濟州大學校 工科大學 産業技術硏究所 1991 産業技術硏究報告 Vol.2 No.-

For the increase of treatment efficiency when waste water which included residual chlorine was biologically treated with activated sludge, elimination efficiency of COD and change of transmittance by activated sludge method were examined after the treatment of residual chlorine with ozone of 100 volt and l0ℓ-air/min., 0.8g-0_(3)/hr. in velocity. The results were as follows. 1) When the sample which included residual chlorine was treated with ozone of 0.8g-O_(3)/hr., COD removal rate by the change of pH and ozonization time was more efficient than acidity solution of pH 3.2(20%) and alkaline solution of pH 12.0(10%). Since the COD removal rate become 35% after 50 minutes of ozonization time at neutral solution of pH 7.2. 2) After the residual chlorine included sample was treated with ozone for 50 minutes to make the F/M rate of 0.1㎏·BOD/㎏·MLSS, the sample was reacted with activated sludge for 3, 6, 9 and 15 hours. The 6 hours reaction gave 85.8% COD elimination which showed higher efficiency than 60.5% by Na_(2)S_(2)O_(3) treatment togather with shorting efficiency of reaction time. 3) When such sample as polyphenol which gives dark brown color was treated with ozone for 50 minutes after being made into acidic, neutral and alkaline solution. the transmittance increased from 30- 40% to 70% and gave better result in alkaline solution.

Centerless Feeder 장치의 개발

강형모,권경우,김기길,정의식,허영환 한밭대학교 산업과학기술연구소 1994 논문집 Vol.2 No.-

This paper presents results of the development of centerless feeding system which are applicable to bearing metal processes. As a result, the feeding system can be applied to automatic surface finishing on the bearing metal process such as bush, and has greatly effects on the increase of the prodnctiving and the decrease of the man power an effect on increase the productivity and decrease the man power and effect on increase the productivity and decrease the man power of the bush machining process.

전도도계의 제작에 관한 연구

강용환,최석남,박병빈 공주대학교 사범대학 과학교육연구소 1980 과학교육연구 Vol.12 No.1

A low-cost student type conductance meter have been developed for the measurement of conductivity of electrochemical system. This instrument measures an impedance range from ?? Ohm with 2% accuracy. And this instrument could be applied to measure the rapid chemical reaction.

치환된 알킬요드화물 또는 크산테이트 화합물과 에틸 아크릴산 또는 메틸 비닐케톤과의 분자간 라디칼 탄소-탄소 결합형성반응

강석구,박영원,박천호,조일환,오원택 성균관대학교 1992 論文集 Vol.42 No.2

생리활성천연물인 lipoxin A, carpenter bee 페로몬, 뇌염모기 페로몬, exobrevicomin 등의 합성의 주요 키탈 중간체들을 치환된 요드화물 또는 크산테이트 화합물과 에틸아크릴산 또는 메틸비닐케톤과의 분자간 라디칼 탄소-탄소 형성 반응에 의해 합성하였다. The chiral building blocks for the synthesis of biologically active natural products such as lipoxin A, carpenter bee pheromone, mosquito ov-iposition pheromone, and exo-brevicomins were synthesized by intermol-ecular radical C-C bond formation of the appropriate substituted iodides or xanthates with ethyl acrylate or methyl vinyl ketone.

食品工場廢水의 活性汚泥處理中 오존에 依한 酸化分解效果

康京壽,崔永贊,宋大鎭,河璡桓 濟州大學校工科大學附屬産業技術硏究所 1991 尖端技術硏究所論文集 Vol.2 No.-

잔류염소를 함유한 發水를 活性汚泥에 의한 處理效率을 增加시키기 위하여 전압 100Volt, 유속 10ℓ-air/min, 0.8g-O₃/hr의 오존으로 처리했을때 COD의 除去效果및 투과율의 變化를 實驗한 結果를 要約하면 다음과 같다. 1. 잔류염소를 함유한 시료를 0.8g-O₃/hr의 오존으로 處理하였을때 pH의 變化 및 反應時間에 의한 COD의 除去率은 中性溶液(pH=7.2)에서 오존處理時間 50分 후 35%의 除去效果를 나타내어 酸性溶液(pH=3.2)의 20%, 알칼리性溶液(pH=12.0)의 10%의 除去效果보다 좋았다. 2. 잔류염소를 함유한 試料를 오존으로 50分間 處理하여 F/M比 0.1㎏·BOD/㎏·MLSS로 한 후 3. 6. 9 및 15時間 活性汚泥로 反應시켰을 때 反應時間 6時間 후 85.8%의 COD의 除去效果가 있어 티오황산나트륨(Na₂S₂O₃)으로 處理한 試料의 除去率 60.5%보다 좋았으며, 反應時間의 단축효과도 있었다. 3. Polyphenol色素 等 暗褐色을 띄는 試料를 酸性, 中性, 알칼리性 溶液으로 하여 오존으로 50分間 處理하였을 때 투과율이 30~40%에서 70% 以上 상승하였으며 알칼리성溶液에서가 투과율이 더 좋았다. For the increase of treatment efficiency when waste water which included residual chlorine was biologically treated with activated sludge, elimination efficiency of COD and change of transmittance by activated sludge method were examined after the treatment of residual chlorine with ozone of 100 volt and 10ℓ-air/min., 0.8g-O₃/hr. in velocity. The results were as follows. 1) When the sample which included residual chlorine was treated with ozone of 0.8g-O₃/hr., COD removal rate by the change of pH and ozonization time was more efficient than acidity solution of pH 3.2(20%) and alkaline solution of pH 12.0(10%). Since the COD removal rate become 35% after 50 minutes of ozonization time at neutral solution of pH 7.2. 2) After the residual chlorine included sample was treated with ozone for 50 minutes to make the F/M rate of 0.1㎏·BOD/㎏·MLSS, the sample was reacted with activated sludge for 3, 6, 9 and 15 hours. The 6 hours reaction gave 85.8% COD elimination which showed higher efficiency than 60.5% by Na₂S₂O₂ treatment togather with shorting efficiency of reaction time. 3) When such sample as polyphenol which gives dark brown color was treated with ozone for 50 minutes after being made into acidic, neutral and alkaline solution, the transmittance increased from 30-40% to 70% and gave better result in alkaline solution.

질의문 키워드의 가중치 부여 방법을 이용한 정답 문서 순위화 시스템

강유환,안영민,서영훈 충북대학교 컴퓨터정보통신 연구소 2005 컴퓨터정보통신연구 Vol.13 No.1

본 논문에서는 자연어로 된 질의문에 대한 키워드 추출 및 가중치 부여 방법을 이용하여 정답 문서를 상위로 순위화하는 방법을 제안한다. 정답 문서를 상위로 순위화하기 위해 자연어 질의문과 정답 문서에서 나타나는 키워드의 특성을 분석하고, 색인어로써 중요한 역할을 할 수 있는 키워드를 다양한 형태로 추출한 후, 추출된 키워드에 차별화된 가중치를 부여한다. 끝으로 문서에 나타난 키워드의 출현 횟수와 문서 가중치를 이용하여 문서를 순위화한다. 실험에서는 20개의 질의문에 대해 상위 5위 안에 들어 있는 정답 문서의 수를 측정하였다. 실험결과 상위 5위 안에 들어 있는 정답 문서의 평균 개수는 3.05개로 키워드의 출현횟수와 키워드의 근접상을 이용한 방법보다 높은 성능 향상을 보였다. This paper describes a method of weighting keywords in the question that is written in a natural language for ranking answer documents. We extract keywords from the question using characteristic of question and keywords that are used in answer documents. And we assign differentiated weight to each keyword. Finally, we rank documents in order that answer documents can be ranked in high position using frequency of keywords and weight of documents. In experiment, we tested the number of answer documents that are ranked in top 5 for 20 questions. Experimental results show that the average number of answer documents that are ranked in top 5 was 3.05 and the accuracy of the proposed method was improved comparing with the existing method using frequency and proximity of keywords.