• 한국식품과학회지
• /
• 제33권1호
• /
• pp.66-71
• /
• 2001

가열에 의한 품종별 고구마 조직의 변화에 대한 반응속도론적 상수를 biphasic model과 fractional conversion method를 사용하여 결정하였다. Biphasic model에 따라 고구마의 가열에 의한 조직의 변화는 2단계의 연속적인 1차 반응식으로 표시할 수 있었으며, 활성화에너지는 고구마의 품종에 따라 $71.0{\sim}75.1\;kJ/mol$ 및 $48.4{\sim}59.6\;kJ/mol$이었다. 또한 고구마의 가열에 의한 조직변화를 fractional conversion method를 사용하여 1개의 1차 반응식으로 표시할 수 있었는데, 이 때의 활성화에너지는 $67.5{\sim}75.3\;kJ/mol$로서 biphasic model에 의한 제 1단계의 반응에 대한 값과 유사한 값을 나타냈다. 이들 방법으로 결정된 반응속도론적 상수들 사이에는 kinetic compensation 효과가 있었으며, 두 방법 모두 고구마의 가열에 의한 조직변화에 대한 반응속도론적 상수들을 결정하는데 적용할 수 있음을 알 수 있었다.

• The Korean Journal of Physiology and Pharmacology
• /
• 제27권6호
• /
• pp.541-553
• /
• 2023

Retinal prostheses have shown some clinical success in restoring vision in patients with retinitis pigmentosa. However, the post-implantation visual acuity does not exceed that of legal blindness. The reason for the poor visual acuity might be that (1) degenerate retinal ganglion cells (RGCs) are less responsive to electrical stimulation than normal RGCs, and (2) electrically-evoked RGC spikes show a more widespread not focal response. The single-biphasic pulse electrical stimulation, commonly used in artificial vision, has limitations in addressing these issues. In this study, we propose the benefit of multiple consecutive-biphasic pulse stimulation. We used C57BL/6J mice and C3H/HeJ (rd1) mice for the normal retina and retinal degeneration model. An 8 × 8 multi-electrode array was used to record electrically-evoked RGC spikes. We compared RGC responses when increasing the amplitude of a single biphasic pulse versus increasing the number of consecutive biphasic pulses at the same stimulus charge. Increasing the amplitude of a single biphasic pulse induced more RGC spike firing while the spatial resolution of RGC populations decreased. For multiple consecutive-biphasic pulse stimulation, RGC firing increased as the number of pulses increased, and the spatial resolution of RGC populations was well preserved even up to 5 pulses. Multiple consecutive-biphasic pulse stimulation using two or three pulses in degenerate retinas induced as much RGC spike firing as in normal retinas. These findings suggest that the newly proposed multiple consecutive-biphasic pulse stimulation can improve the visual acuity in prosthesis-implanted patients.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
• /
• pp.277-284
• /
• 2004

Batch experiments were conducted to investigate the sorption and desorption behaviors of PAHs (naphthalene, phenanthrene and pyrene) in soils. Three different soils montmorillonite KSF (foc =0.14%), masato (foc =0.08%), and diatomite (foc =0.007%) were investigated. The results of sorption-desorption experiment indicate that the sorption affinity of PAHs was in the order of montmorillonite > masato > diatomite. The Freundlich model was well fitted to the sorption and desorption data. Sorption affinity increased as loc increased. Desorption of PAHs from soils was biphasic composed of reversible and irreversible compartments. Desorption-resistance of phenanthrene in soils was also determined. The biphasic desorption model was used to explain desorption-resistance of phenanthrene in soils. The linear term represents reversible sorption fraction and Langmuinian-type term represents desorption-resistant fraction.

• Journal of Microbiology and Biotechnology
• /
• 제27권2호
• /
• pp.297-305
• /
• 2017

The use of peroxidase in the nitration of phenols is gaining interest as compared with traditional chemical reactions. We investigated the kinetic characteristics of phenol nitration catalyzed by horseradish peroxidase (HRP) in an aqueous-organic biphasic system using n-butanol as the organic solvent and ${NO_2}^-$ and $H_2O_2$ as substrates. The reaction rate was mainly controlled by the reaction kinetics in the aqueous phase when appropriate agitation was used to enhance mass transfer in the biphasic system. The initial velocity of the reaction increased with increasing HRP concentration. Additionally, an increase in the substrate concentrations of phenol (0-2 mM in organic phase) or $H_2O_2$ (0-0.1 mM in aqueous phase) enhanced the nitration efficiency catalyzed by HRP. In contrast, high concentrations of organic solvent decreased the kinetic parameter $V_{max}/K_m$. No inhibition of enzyme activity was observed when the concentrations of phenol and $H_2O_2$ were at or below 10 mM and 0.1 mM, respectively. On the basis of the peroxidase catalytic mechanism, a double-substrate ping-pong kinetic model was established. The kinetic parameters were ${K_m}^{H_2O_2}=1.09mM$, ${K_m}^{PhOH}=9.45mM$, and $V_{max}=0.196mM/min$. The proposed model was well fit to the data obtained from additional independent experiments under the suggested optimal synthesis conditions. The kinetic model developed in this paper lays a foundation for further comprehensive study of enzymatic nitration kinetics.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제42권
• /
• pp.34.1-34.7
• /
• 2020

Purpose: The purpose of this study was to evaluate the influence of biodegradable polycaprolactone membrane on new bone formation and the biodegradation of biphasic alloplastic bone substitutes using animal models. Materials and methods: In this study, bony defect was formed at the canine mandible of 8 mm in diameter, and the defects were filled with Osteon II. The experimental groups were covered with Osteoguide as barrier membrane, and the control groups were closed without membrane coverage. The proportion of new bone and residual bone graft material was measured histologically and histomorphometrically at postoperative 4 and 8 weeks. Results: At 4 weeks, the new bone proportion was similar between the groups. The proportion of remaining graft volume was 27.58 ± 6.26 and 20.01 ± 4.68% on control and experimental groups, respectively (P < 0.05). There was no significant difference between the two groups in new bone formation and the amount of residual bone graft material at 8 weeks. Conclusion: The biopolymer membrane contributes to early biodegradation of biphasic bone substitutes in the jaw defect but it does not affect the bone formation capacity of the bone graft.

• Journal of Industrial and Engineering Chemistry
• /
• 제68권
• /
• pp.220-228
• /
• 2018

In this study, we found a simple surface biofunctionalization of biphasic calcium phosphate (BCP) based on the high affinity between alendronate and the calcium ions of BCP, and the strong interaction between heparin and bone morphogenic protein-2 (BMP-2). The biofunctionalized BCP did not be precipitated well and display a remarkable enhancement of osteogenic activity of human adipose-derived stem cells by showing increased alkaline phosphatase (ALP), calcium deposition and osteogenic-related genes (i.e., Runx-2, ALP, osteocalcin, and osteopontin), and bone regeneration in the calvarial defect model. Therefore, this simple surface technique can be used to easily functionalize various calcium phosphates.

• 대한본초학회지
• /
• 제27권4호
• /
• pp.33-44
• /
• 2012

Objectives : There is a pressing need to determine the clinical and scientific validity of herbal therapies for animal model with atopic dermatitis since some differences in systemic cytokine polarization between in animal model and in patients with atopic dermatitis has been reported. New studies for tang, medicinal herb itself or effective ingradients of medicinal herb showing anti-atopic dermatitis effectiveness are reviewed in terms of cytokine regulation. Methods : Those herbal therapies used to treat atopic dermatitis in animal model were introduced and the expression pattern of cytokine and the activity of mast cell were compared in both animal model and patients with atopic dermatitis. Results : In case of atopic dermatitis in human, there is a biphasic pattern of cytokine expression in atopic dermatitis, with acute skin inflammation associated with a predominance of IL-4 and IL-13 expression from Th2 cells, and chronic inflammation associated with increased IL-5 from Th2-cells and IFN-${\gamma}$ from Th1-cells. However, a pattern of cytokine expression in animal model with atopic dermatitis is not matched well to the biphasic pattern of cytokine expression in patients with atopic dermatitis. In addition, a kind of cytokine is different by animal model with atopic dermatitis. These differences would make herbal medicines, showing their effectiveness on atopic dermatitis, difficult to apply to patients with atopic dermatitis. Conclusion : The pattern of local cytokine expression plays an important role in modulating tissue inflammation, and in atopic dermatitis this pattern depends on the acuity or duration of the skin lesion. Thus, in order to develop medicinal herb itself or effective ingradients of medicinal herb showing anti-atopic dermatitis effectiveness, biphasic pattern of cytokine expression should be considered in animal model with atopic dermatitis.

• Journal of Periodontal and Implant Science
• /
• 제49권2호
• /
• pp.114-126
• /
• 2019

Purpose: The aim of this study was to evaluate the enhancement of osteogenic potential of biphasic calcium phosphate (BCP) bone substitute coated with Escherichia coli-derived recombinant human bone morphogenetic protein-2 (ErhBMP-2) and epigallocatechin-3-gallate (EGCG). Methods: The cell viability, differentiation, and mineralization of osteoblasts was tested with ErhBMP-2-/EGCG solution. Coated BCP surfaces were also investigated. Standardized, 6-mm diameter defects were created bilaterally on the maxillary sinus of 10 male New Zealand white rabbits. After removal of the bony windows and elevation of sinus membranes, ErhBMP-2-/EGCG-coated BCP was applied on one defect in the test group. BCP was applied on the other defect to form the control group. The animals were sacrificed at 4 or 8 weeks after surgery. Histologic and histometric analyses of the augmented graft and surrounding tissue were performed. Results: The 4-week and 8-week test groups showed more new bone (%) than the corresponding control groups (P<0.05). The 8-week test group showed more new bone (%) than the 4-week test group (P<0.05). Conclusions: ErhBMP-2-/EGCG-coated BCP was effective as a bone graft material, showing enhanced osteogenic potential and minimal side effects in a rabbit sinus augmentation model.

• 대한의용생체공학회:의공학회지
• /
• 제39권1호
• /
• pp.22-29
• /
• 2018

Intervertebral disc(IVD) mainly consists of Annulus fibrosus(AF) and Nucleus pulposus(NP), playing a role of distributing a mechanical load on vertebral body. IVD tissue engineering has been developed the methods to achieve anatomic morphology and restoration of biological function. The goal of present study is to identify the possibilities for creating a substitute of IVD the morphology and biological functions are the same as undamaged complete IVD. To fabricate the AF and NP combine biphasic IVD tissue, AF tissue scaffolds have been printed by 3D bio-printing system with natural biomaterials and NP tissues have been prepared by scaffold-free culture system. We evaluated whether the combined structure of 3D printed AF scaffold and scaffold-free NP tissue construct could support the architecture and cell functions as IVD tissue. 3D printed AF scaffolds were printed with 60 degree angle stripe patterned lamella structure(the inner-diameter is 5mm, outer-diameter is 10 mm and height is 3 mm). In the cytotoxicity test, the 3D printed AF scaffold showed good cell compatibility. The results of histological and immunohistochemical staining also showed the newly synthesized collagens and glycosaminoglycans, which are specific makers of AF tissue. And scaffold-free NP tissue actively synthesized glycosaminoglycans and type 2 collagen, which are the major components of NP tissue. When we combined two engineered tissues to realize the IVD, combined biphasic tissues showed a good integration between the two tissues. In conclusion, this study describes the fabrication of Engineered biphasic IVD tissue by using enable techniques of tissue engineering. This fabricated biphasic tissue would be used as a model system for the study of the native IVD tissue. In the future, it may have the potential to replace the damaged IVD in the future.

• 한국환경과학회지
• /
• 제24권11호
• /
• pp.1393-1404
• /
• 2015

Ten empirical disinfection models for the plasma process were used to find an optimum model. The variation of model parameters in each model according to the operating conditions (first voltage, second voltage, air flow rate, pH, incubation water concentration) were investigated in order to explain the disinfection model. In this experiment, the DBD (dielectric barrier discharge) plasma reactor was used to inactivate Phytophthora capsici which cause wilt in tomato plantation. Optimum disinfection models were chosen among ten models by the application of statistical SSE (sum of squared error), RMSE (root mean sum of squared error), $r^2$ values on the experimental data using the GInaFiT software in Microsoft Excel. The optimum models were shown as Log-linear+Tail model, Double Weibull model and Biphasic model. Three models were applied to the experimental data according to the variation of the operating conditions. In Log-linear+Tail model, $Log_{10}(N_o)$, $Log_{10}(N_{res})$ and $k_{max}$ values were examined. In Double Weibull model, $Log_{10}(N_o)$, $Log_{10}(N_{res})$, ${\alpha}$, ${\delta}_1$, ${\delta}_2$, p values were calculated and examined. In Biphasic model, $Log_{10}(N_o)$, f, $k_{max1}$ and $k_{max2}$ values were used. The appropriate model parameters for the calculation of optimum operating conditions were $k_{max}$, ${\alpha}$, $k_{max1}$ at each model, respectively.