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Advanced Organotypic In Vitro Model Systems for Host–Microbial Coculture
김래현 한국바이오칩학회 2023 BioChip Journal Vol.17 No.2
In vitro model systems have been advanced to recapitulate important physiological features of the target organ in vivo more closely than the conventional cell line cultures on a petri dish. The advanced organotypic model systems can be used as a complementary or alternative tool for various testing and screening. Numerous data from germ-free animal studies and genome sequencings of clinical samples indicate that human microbiota is an essential part of the human body, but current in vitro model systems rarely include them, which can be one of the reasons for the discrepancy in the tissue phenotypes and outcome of therapeutic intervention between in vivo and in vitro tissues. A coculture model system with appropriate microbes and host cells may have great potential to bridge the gap between the in vitro model and the in vivo counterpart. However, successfully integrating two species in one system introduces new variables to consider and poses new challenges to overcome. This review aims to provide perspectives on the important factors that should be considered for developing organotypic bacterial coculture models. Recent advances in various organotypic bacterial coculture models are highlighted. Finally, challenges and opportunities in developing organotypic microbial coculture models are also discussed.
김래현,손요환,황재홍 한국생태학회 2004 Journal of Ecology and Environment Vol.27 No.2
Coarse woody debris (CWD, ≥ 5 cm in maximum diameter) is an important functional component, especially to nutrient cycling in forest ecosystems. To compare mass and nutrient dynamics of CWD in natural oak forests, a two-year study was conducted at Quercus serrata and Q. variabilis stands in Yangpyeong, Kyonggi Province. Total CWD (snag, stump, log and large branch) and annual decomposition mass (Mg/ha) were 1.9 and 0.4 for the Q. serrata stand and 7.5 and 0.5 for the Q. variabilis stand, respectively. Snags covered 72% of total CWD mass for the Q. variabilis stand and 42% for the Q. serrata stand. Most of CWD was classified into decay class 1 for both stands. CWD N and P concentrations for the Q. variabilis stand significantly increased along decay class and sampling time, except for P concentration in 2002. There were no differences in CWD N concentration for the Q. serrata stand along decay class and sampling time. However, CWD P concentration decreased along sampling time. CWD N and P contents (kg/ha) ranged from 3.5~4.7 and 0.8~1.3 for the Q. serrata stand to 22.8~23.6 and 3.7~4.7 for the Q. variabilis stand. Nitrogen and P inputs (kg/ha/yr) into mineral soil through the CWD decomposition were 0.7 and 0.3 for the Q. serrata stand and 1.6 and 0.3 for the Q. variabilis stand, respectively. The number of CWD and decay rate were main factors influencing the difference in CWD mass and nutrient dynamics between both stands.
김래현,박세형 한국정보과학회 2004 정보과학회논문지 : 시스템 및 이론 Vol.31 No.12
We present a novel haptic sculpting system where the user intuitively adds to and carves out material from a volumetric model using new sculpting tools in the similar way to handling real clay. Haptic rendering and model deformation are implemented based on volumetric implicit surface. We enhance previous volume-based haptic sculpting systems by presenting fast and stable force computation on 3D models to be deformed. In order to bridge the gap between fast haptic process (1 KHz) and much slower visual update frequency(∼30Hz), the system generates intermediate implicit surfaces between two consecutive physical models being deformed. It performs collision detection and force computation on the intermediate surface in haptic process. The volumetric model being sculpted is visualized as a geometric model which is adaptively polygonized according to the surface complexity. We also introduce various visual effects for the real-time sculpting system including mesh-based solid texturing, painting, and embossing/engraving techniques. 본 논문에서는 햅틱 인터페이스를 통해 실제 찰흙을 만지는 것처럼 자연스럽게 가상 모델의 일부를 덧붙이거나 제거하여 원하는 모양을 만드는 햅틱 가상 조각 시스템을 소개하고자 한다. 햅틱 렌더링과 햅틱 툴에 의한 가상 모델의 변형은 볼륨 간접 표면 법을 기반으로 이루어 진다. 본 시스템에서는 기존의 불륨 데이타 기반의 햅틱 조각 시스템이 갖는 문제점들을 개선하고 빠르고 안정된 알고리즘을 제안하였다. 먼저 가상의 물체를 조각하는 동안 빠른 햅틱 응답 속도(1 KHz)에 비해 훨씬 느린 비쥬얼 프로세싱(∼30 Hz)의 속도 차이로 인해 발생되는 문제를 극복하기 위해 조각과정의 연속적인 두 모델의 중간 표면 들을 생성하여 부드러운 햅틱 렌더링을 구현하였다. 조각 툴에 의해 변형되는 불륨 간접 표면은 비쥬얼 디스플레이를 위해 메쉬 모델로 컨버전 되는데 이때 메쉬 모델은 표면의 복잡도를 반영하여 적은 폴리곤으로 복잡한 모양을 보여줄 수 있는 비 균일 메쉬 생성 기법을 사용하였다. 실시간 조각과정에서 가상 물체의 다양한 비쥬얼 효과를 위해 메쉬 기반의 솔리드 텍스쳐링, 페인팅, 그리고 모델의 양각/음각 기법도 구현하였다.
술폰화 poly(arylene ether sulfones) 양이온 교환막의 술폰산기 농도 변화에 따른 특성
김래현,이승용,최선용,이정우,박세용,Kim Lae Hyun,Lee Seung Yong,Choi Sun Yong,Lee Joung Woo,Park Sei Yong 한국전기화학회 2000 한국전기화학회지 Vol.3 No.1
이온 교환막의 고정이온 농도변화에 따른 막 특성을 알아보기 위해 matrix인 PSF (polysulfone)과 술폰화제인 CSA(chlorosulfuric acid)의 몰 비를 달리하여 SPSF (sulfonated polysulfone) 양이온 교환수지를 합성하였다. 합성된 SPSF의 이온교환용량, 함수율, 고정이온 농도, 분배계수 등을 측정하였다. DSC, TGA분석으로부터 SPSF의 술폰산기 농도 증가에 따라 벌키한 술폰산기의 도입으로 인하여 유리전이 온도는 증가하고 중량 감소비는 감소하는 것으로 나타났다. 본 실험조건에서는 SPSF막의 구조가 SEM, AFM등의 분석을 통하여 비대칭인 것으로 나타났다. 교류 임피던스로부터 측정한 SPSF 막을 통한 $Na^+$ 이온의 겉보기 확산계수는 술폰산기 농도 증가에 따라 증가하였다. Sulfonated Polysulfone (SPSF) cation-exchange membranes were synthesized by introducing various ratio of chlorosulfuric acid (CSA) onto the main chain of polysulfone (PSF). Properties such as ion exchange capacity, water content, liked ion concentration, and partition coefficient were measured, respectively. Through the analysis of DSC and TGA, it has been shown that glass transition temperature increased and weight loss decreased as sulfuric acid group concentration increased. Structure of membrane measured by AFM and SEM was seen to be asymmetric. Apparent diffusion coefficient of sodium ions through SPSF membrane by AC impedance was increased as sulfuric acid group concentration increased.