• 대한의용생체공학회:의공학회지
• /
• 제8권2호
• /
• pp.111-116
• /
• 1987

In this study, basilar membrane motions and neural tuning responses are analysed with I-dimensional equations for cochlear fluid mechanics and an active cochlear model. The results are as follows. (1) The differences between basilar membrane motions in an active cochlear model and in an passive cochlear model are explained. (2) The basilar membrane motion curves and the neur'at tuning curves which are in accordance with physiological measurements ave obtained. (3) It is proved that the active mechanism makes cochlear highly frequency sensitive.

• Molecules and Cells
• /
• 제28권5호
• /
• pp.473-477
• /
• 2009

Previously, the 9-mer analog peptides, 9Pbw2 and 9Pbw4, were designed based on a defensin-like peptide, protaetiamycine isolated from Protaetia brevitarsis. In this study, antifungal effects of the analog peptides were investigated. The antifungal susceptibility testing exhibited that 9Pbw4 contained more potent antifungal activities than 9Pbw2. A PI influx assay confirmed the effects of the analog peptides and demonstrated that the peptides exerted their activity by a membrane-active mechanism, in an energy-independent manner. As the noteworthy potency of 9Pbw4, the mechanism(s) of 9Pbw4 were further investigated. The membrane studies, using rhodamine-labeled giant unilamellar vesicle (GUV) and fluorescein isothiocyanate (FITC)-dextran loaded liposome, suggested that the membrane-active mechanism of 9Pbw4 could have originated from the pore-forming action and the radii of pores was presumed to be anywhere from 1.8 nm to 3.3 nm. These results were confirmed by 3D-flow cytometric contour-plot analysis. The present study suggests a potential of 9Pbw4 as a novel antifungal peptide.

• 멤브레인
• /
• 제17권1호
• /
• pp.14-22
• /
• 2007

본 연구는 투과증발법을 이용하여 수용액 중 미량의 목련 향 성분을 농축하는 방법으로, PVDF/PDMS 복합막을 제조하여 지지막의 구조와 활성층의 두께에 따른 분리능의 변화를 살펴보았다. PVDF 지지막은 제막조건인 응고액의 온도가 감소하고 고분자 농도가 증가함에 따라 지지층에서의 표면공극률과 기공의 직경이 감소함을 순수투과실험을 통해서 간접적으로 확인하였고, 복합막에 대한 지지막 구조의 영향을 투과 mechanism식에 적용하여 해석하였다. 또한 PDMS의 두께가 증가됨에 따라 선택도가 증가하는 결과를 통해서, 활성층에서의 물질전달을 Fick's law에 의하여 설명하는데 제한이 있음을 알 수 있었다.

• 한국막학회:학술대회논문집
• /
• 한국막학회 1991년도 추계 총회 및 학술발표회
• /
• pp.4-8
• /
• 1991

The characterization of pore properties (mean pore size and pore size distribution) of the active layer in a UF membrane is important not only in order to obtain information about the factors affecting pore formation during membrane manufacturing but also to understand deeply the mechanism of solute and solvent transport through pores. Many methods of characterizing quantitatively the pore properties of UF membranes have been suggested in the literature: solvent and gas flow measurement, bubble point determination, electron microscopy, gas adsorption/desorption measurement, rejection measurement etc. But most of these methods involve time-consuming procedures and involve some wellknown problems and uncertainties.

• Journal of Microbiology and Biotechnology
• /
• 제22권11호
• /
• pp.1457-1466
• /
• 2012

Antimicrobial peptides (AMPs) exert antimicrobial activity against Gram-positive and Gram-negative bacteria, fungi, and viruses by various mechanisms. AMPs commonly possess particular characteristics by harboring cationic and amphipathic structures and binding to cell membranes, resulting in the leakage of essential cell contents by forming pores or disturbing lipid organization. These membrane disruptive mechanisms of AMPs are possible to explain according to the various structure forming pores in the membrane. Some AMPs inhibit DNA and/or RNA synthesis as well as apoptosis induction by reactive oxygen species (ROS) accumulation and mitochondrial dysfunction. Specifically, mitochondria play a major role in the apoptotic pathway. During apoptosis induced by AMPs, cells undergo cytochrome c release, caspase activation, phosphatidylserine externalization, plasma or mitochondrial membrane depolarization, DNA and nuclei damage, cell shrinkage, apoptotic body formation, and membrane blebbing. Even AMPs, which have been reported to exert membrane-active mechanisms, induce apoptosis in yeast. These phenomena were also discovered in tumor cells treated with AMPs. The apoptosis mechanism of AMPs is available for various therapeutics such as antibiotics for antibiotic-resistant pathogens that resist to the membrane active mechanism, and antitumor agents with selectivity to tumor cells.

• KSBB Journal
• /
• 제6권3호
• /
• pp.241-247
• /
• 1991

본 연구에서는 고정전달자를 갖는 poly(4-vinylpyridine-co-styrene) 고분자막을 합성하여 이를 특성화하고, $Cl^-$ 및 $CCl_3COO$ 의 $H^+$ 및 $OH^-$ 농도차에 따른 능동전달 기구에 대하여 고찰하였다. 시험 범위 내에서 $Cl^-$의 능동전달은 주로 $H^+$ 농도차를 구동력으로 한 병류수송(symprot)이 주가 되었으며 반면에 $CCl_3COO^{-}$의 능동전달은 $OH^-$의 농도차에 의한 향류 수성(antiport)의 영향이 큼을 알 수 있었다. $H^+$ 농도와 $OH^-$ 농도에 의한 음이온의 초기플럭스를 관찰함으로서, 고정전달자와 이온간의 엄형성계수, K와 이온의 막내 확산계수, D는 $Cl^-$의 경우 각각 $4.60{\times}10^2\;mol^{-1}{\cdot}\textrm{cm}^3$ 및 $1.57{\times}10^3{\textrm{cm}^2}/h$, $CCl_3COO^{-}$의 경우 각각 $1.10{\times}10^4\;mol^{-1}{\cdot}\textrm{cm}^3$ 및 $1.44{\times}10^4{\textrm{cm}^2}/h$ 이었다.

• Journal of Microbiology and Biotechnology
• /
• 제25권6호
• /
• pp.759-764
• /
• 2015

Antimicrobial peptides (AMPs) are one of the critical components in host innate immune responses to imbalanced and invading microbial pathogens. Although the antimicrobial activity and mechanism of action have been thoroughly investigated for decades, the exact biological properties of AMPs are still elusive. Most AMPs generally exert the antimicrobial effect by targeting the microbial membrane, such as barrel stave, toroidal, and carpet mechanisms. Thus, the mode of action in model membranes and the discrimination of AMPs to discrepant lipid compositions between mammalian cells and microbial pathogens (cell selectivity) have been studied intensively. However, the latest reports suggest that not only AMPs recently isolated but also well-known membrane-disruptive AMPs play a role in intracellular killing, such as apoptosis induction. In this mini-review, we will review some representative AMPs and their antimicrobial mechanisms and provide new insights into the dual mechanism of AMPs.

• 한국막학회:학술대회논문집
• /
• 한국막학회 1995년도 추계 총회 및 학술발표회
• /
• pp.43-44
• /
• 1995

The diffusion behavior of liquid into polymer has been described by Fick's law, but the departure from Fickian diffusion is frequently found. In this study, 'noble' expressions for the rates of relaxation and sorption are introduced to eliminate these limitations. The ralaxation-sorption coupled mechanism model are based on the possibility of contacting liquid molecule and the active site which has the numerical concept of free volume. The concept has an analogy of reaction rate expressed by the possibility of collision with molecules and used in adsorption and reactive extraction etc. The new model simulated by Rungc-Kutta method for initial-value problem and Fickian diffusion is caompared with experimental data. The results show that the ralaxation-sorption coupled mechanism is able to account well for Fickian and non-Fickian sorption behavior including sigmoid and two-stage. In addition, this model has a chance of expansion to multi-component sorption with ease.

• 한국막학회:학술대회논문집
• /
• 한국막학회 1996년도 춘계 총회 및 학술발표회
• /
• pp.16-19
• /
• 1996

Separation with synthetic membrane have become increasingly important processes in many fields. In the most application of membrane process, polymer membrane is used. the main advantage of polymers as a material for membrane preparation is the relative simplicity of this film formation which enables one to obtain rather high permeability rates. However, polymeric membranes have several limitations, such as high temperature instability, swelling and decomposition in organic solvent, et. al.. These limitations can be overcome by inorganic membrane. At the present time, commercially available inorganic membranes have pore diameters ranging 5nm to 50mm, and the predominant flow regime in such membrane is Knudsen diffusion. Since the Knudsen permeability is directly proportional to the molecular velocity, gases can be separated due to their molecular masses. However, this separation mechanism is only of important for light gases such as H2 and He. Other separation mechanisms like surface diffusion, active diffusion can play an important role only with very small pore diameters(2nm) and give rise to large permselectivities. Therefore, preparation of inorganic membrane with nano-sized pore have been attracting more and more attention.

• 한국막학회:학술대회논문집
• /
• 한국막학회 1999년도 The 7th Summer Workshop of the Membrane Society of Korea
• /
• pp.55-58
• /
• 1999

Nafion supported catalytic membranes were found to be active, stable and selective in th partial oxidation of propane to oxygenates with H2O2 under mild condition. Addition of Fe2+ in liquid phase enhances the reaction rate. Reaction proceeds according to a radical mechanism based on th electrophilic activation of propane on superacid sites and subsequent reaction of the activated paraffin with OH radicals. The use of a catalytic membrane, which allow separation of the intermediate products from the liquid phase containing the oxidant, was found to be effective to perform selective partial oxidation of propane with high yields to oxygenated products.