• 한국막학회:학술대회논문집
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• 한국막학회 2004년도 Proceedings of the second conference of aseanian membrane society
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• pp.55-58
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• 2004

Cell separation from peripheral blood was investigated using surface-modified polyurethane (PU) membranes with different functional groups. Both red blood cells and platelets could pass through unmodified PU and PU-SO$_3$H membranes, while the red blood cells preferentially passed through PU-N(C$_2$H$_{5}$ )$_2$ and PU-NHC$_2$H$_4$OH membranes. The permeation ratio of T and B cells was less than 25% for the surface-modified and unmodified PU membranes. CD34$^{+}$ cells have been recognized as various kinds of stem cells including hematopoietic and mesenchymal stem cells. The adhesiveness of CD34$^{+}$ cells on the PU membranes was found to be higher than that of red blood cells, platelets, T cells or B cells. Overall, the adhesiveness of blood cells on the PU membranes increased in the following order: red blood cells $\leq$ platelets ＜ T cells $\leq$ B cells ＜ CD34$^{+}$ cells. Treatment of PU-COOH membranes with a human albumin solution to detach adhered blood cells, allowed recovery of mainly CD34$^{+}$ cells in the permeate, while both red blood cells and platelets could be isolated in the permeate using unmodified PU membranes. The PU membranes showed different permeation and recovery ratios of specific cells depending on the functional groups attached to the membranes.mbranes.

• The Journal of Korean Physical Therapy
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• 제29권2호
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• pp.55-61
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• 2017

Purpose: The purpose of this study was to investigate the effects of a task-oriented upper arm exercise performed in a sitting position on either an unstable support surface or a stable support surface for children with cerebral palsy. Methods: We prospectively evaluated 18 children with cerebral palsy. Eight subjects were randomly assigned to each of the stable and unstable support surface groups. We performed the upper arm exercise three times a week for 6 weeks. To confirm the effects of the intervention, the berg balance scale test, modified functional reaching test (MFRT), timed up and go test (TUG), and Jebsen-Taylor hand function test were conducted before and after the study. Results: Significant differences were observed in MFRT and TUG between the experimental and control groups (p<0.05). In the Jebsen-Taylor hand function test, there were significant differences between the groups for the items picking up small objects, stacking checkers, lifting large light objects, and lifting large heavy objects (p<0.05), but not for writing and stimulation of feeding. Significant differences were observed between the groups in items of card turning, lifting large light objects, and lifting heavy objects. Conclusion: The purpose of this study was to evaluate the effectiveness of a task-oriented upper extremity exercise program for dynamic balance and hand function performed in a sitting position with either stable or unstable support by cerebral palsy patients. There were improvements in the two groups, but performing the exercise while sitting on an unstable support surface had a greater effect on dynamic balance and hand function than exercise while sitting on a stable supporting surface. The results of this study can be used to improve the daily lives of cerebral palsy patients.

• 세라미스트
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• 제22권3호
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• pp.230-242
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• 2019

Functional ceramics are widely utilized in a variety of application fields such as structural materials, sensors, energy devices, purification filter and etc due to their high strength, stability and chemical activity. With the breakthrough development of nanotechnology, many researchers have studied new types of nanomaterials including nanoparticle, nanorod, nanowire and nanoplate to realize high-performance ceramics. Especially several groups have focused on the 3D nanostructured ceramics because of their large surface area, efficient load transfer, ultra-fast ion diffusion and superior electrical (or thermal) conductivity. In this review, we introduce the reported fabrication strategies of the 3D nanostructured and functional ceramics, also summarized the 3D nanostructured ceramic based high-performance applications containing photocatalysts, structural materials, energy harvesting and storage devices.

• Korean Chemical Engineering Research
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• 제49권4호
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• pp.443-448
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• 2011

추진제는 저장 중 발생되는 질소산화물로 인해서 저장수명이 짧아진다. 추진제의 저장수명을 연장할 목적으로 활성탄소섬유로 추진제에서 발생하는 질소산화물을 흡착하였다. 활성탄소섬유에 폐추진제를 첨착시키고 열처리하여 표면을 개질한 결과 비표면적이 약간 감소하였으나 피리딘(pyridine), 피리돈(pyridone) 및 피롤(pyrrol) 등의 질소기능기가 생기는 것을 확인하였다. NO에 대한 흡착시험을 통해서 표면개질한 활성탄소섬유의 흡착능이 개질 이전의 활성탄소섬유에 비해 약 2배 증가하였다. 그리고 추진제에 대한 가속수명시험 결과 표면개질한 활성탄소섬유를 동봉하면 추진제의 저장수명이 약 25% 증가하였다.

• 국제물리치료학회지
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• 제11권2호
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• pp.2028-2035
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• 2020

Background: Weakness of the trunk muscles decreases the trunk control ability of stroke patients, which is significantly related to balance and gait. Objectives: To compare the impact of diagonal pattern self-exercise on an unstable surface and a stable surface for trunk rehabilitation on trunk control, balance, and gait ability in stroke patients. Design: Nonequivalent control group design. Methods: Twenty four participants were randomized into the experimental group (diagonal pattern self-exercise while sitting on an unstable surface, n=12) and the control group (diagonal pattern self-exercise while sitting on a stable surface, n=12). All interventions were conducted for 30 minutes, three times a week for four weeks, and the trunk impairment scale (TIS), berg balance scale (BBS), functional gait assessment (FGA), and G-walk were measured. Results: All groups indicated significant increases in all variables (TIS, BBS, FGA, cadence, speed, stride length) after four weeks. The TIS, BBS, FGA, cadence, gait speed, and stride length group-by-time were significantly different between the two groups. Conclusion: We found that, in stroke patients, diagonal pattern self-exercise on an unstable surface is a more effective method for improving trunk control, balance, and gait ability than diagonal pattern self-exercise on a stable surface.

• Carbon letters
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• 제21권
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• pp.1-7
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• 2017

The effects of ammonia-treated graphene oxide (GO) on composites based on epoxy resin were investigated. Ammonia solutions of different concentrations (14-28%) were used to modify GO. Nitrogen functional groups were introduced on the GO surfaces without significant structural changes. The ammonia-treated GO-based epoxy composites exhibited interesting changes in their mechanical properties related to the presence of nitrogen functional groups, particularly amine ($C-NH_2$) groups on the GO surfaces. The highest tensile and impact strength values were 42.1 MPa and 12.3 J/m, respectively, which were observed in an epoxy composite prepared with GO treated with a 28% ammonia solution. This improved tensile strength was 2.2 and 1.3 times higher than those of the neat epoxy and the non-treated GO-based epoxy composite, respectively. The amine groups on the GO ensure its participation in the cross-linking reaction of the epoxy resin under amine curing agent condition and enhance its interfacial bonding with the epoxy resin.

• 대한치과보철학회지
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• 제42권3호
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• pp.307-326
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• 2004

Statement of problem. The long-term success of implants is the development of a stable direct connection between bone and implant surface, which must be structural and functional. To improve a direct implant fixation to the bone, various strategies have been developed focusing on the surface of materials. Among them, altering the surface properties can modify cellular responses such as cell adhesion, cell motility and bone deposition. Purpose. This study was to evaluate the cellular behaviors on the surface-modified titanium by morphological observation, cellular proliferation and differentiation. Material and methods. Specimens were divided into five groups, depending on their surface treatment: electropolishing(EP) anoclizing(AN), machining(MA), blasting with hydroxyapatite particle(RBM) and electrical discharge machining(EDM). Physicochemical properties and microstructures of the specimens were examined and the responses of osteoblast-like cells were investigated. The microtopography of specimens was observed by scanning electron microscopy(SEM). Surface roughness was measured by a three-dimensional roughness measuring system. The microstructure was analyzed by X-ray diffractometer(XRD) and scanning auger electron microscopy(AES). To evaluate cellular responses to modified titanium surfaces, osteoblasts isolated from neonatal rat were cultured. The cellular morphology and total protein amounts of osteoblast-like cell were taken as the marker for cellular proliferation, while the expression of alkaline phosphatase was used as the early differentiation marker for osteoblast. In addition, the type I collagen production was determined to be a reliable indicator of bone matrix synthesis. Results. 1. Each prepared specimen showed specific microtopography at SEM examination. The RBM group had a rough and irregular pattern with reticulated appearance. The EDM-treated surface had evident cracks and was heterogeneous consisting of broad sheet or plate with smooth edges and clusters of small grains, deep pores or craters. 2. Surface roughness values were, from the lowest to the highest, electropolished group, anodized group, machined group, RBM group and EDM group. 3. All groups showed amorphous structures. Especially anodized group was found to have increased surface oxide thickness and EDM group had titaniumcarbide(TiC) structure. 4. Cells on electropolished, anodized and machined surfaces developed flattened cell shape and cells on RBM appeared spherical and EDM showed both. After 14 days, the cells cultured from all groups were formed to be confluent and exhibited multilayer proliferation, often overlapped or stratified. 5. Total protein amounts were formed to be quite similar among all the group at 48 hours. At 14 days, the electropolished group and the anodized group induced more total protein amount than the RBM group(P<.05). 6. There was no significant difference among five groups for alkaline phosphatase(ALP) activity at 48 hours. The AN group showed significantly higher ALP activity than any other groups at 14 days(P<.05). 7. All the groups showed similar collagen synthesis except the EDM group. The amount of collagen on the electropolished and anodized surfaces were higher than that on the EDM surface(P<.05).

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권3호
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• pp.218-224
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• 2005

Surface modification of glutaraldehyde fixed bovine pericardium (GFBP) was success­fully carried out with hyaluronic acid (HA) derivatives. At first, HA was chemically modified with adipic dihydrazide (ADH) to introduce hydrazide functional group into the carboxyl group of HA backbone. Then, GFBP was surface modified by grafting HA-ADH to the free aldehyde groups on the tissue and the subsequent HA-ADH hydrogel coating. HA-ADH hydrogels could be prepared through selective crosslinking at low pH between hydrazide groups of HA-ADH and crosslinkers containing succinimmidyl moieties with minimized protein denaturation. When HA­ADH hydrogels were prepared at low pH of 4.8 in the presence of erythropoietin (EPO) as a model protein, EPO release was continued up to $85\%$ of total amount of loaded EPO for 4 days. To the contrary, only $30\%$ of EPO was released from HA-ADH hydrogels prepared at pH=7.4, which might be due to the denaturation of EPO during the crosslinking reaction. Because the carboxyl groups on the glucuronic acid residues are recognition sites for HA degradation by hyaluronidase, the HA-ADH hydrogels degraded more slowly than HA hydrogels prepared by the crosslinking reaction of divinyl sulfone with hydroxyl groups of HA. Following a two-week subcutaneous implantation in osteopontin-null mice, clinically significant levels of calcification were observed for the positive controls without any surface modification. However, the calcification of surface modified GFBP with HA-ADH and HA-ADH hydrogels was drastically reduced by more than $85\%$ of the positive controls. The anti-calcification effect of HA surface modification was also confirmed by microscopic analysis of explanted tissue after staining with Alizarin Red S for calcium, which followed the trend as observed with calcium quantification.

• 대한의용생체공학회:의공학회지
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• 제14권3호
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• pp.209-220
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• 1993

Microspheres are expected to be applied to biomedical areas such as solid-phase immunoassays, drug delivery systems, Immunomagnetic cell separation. To synthesize micro-spheres for biomedical application, "two stage shot growth method" was developed. The uniformity ratio or synthesized microspheres was always smatter than 1.05. And the surface charge density (or the number of ionizable functional groups) of the microspheres synthesized by "two stage shot growth method" was 6-13 times higher than thats of the ml crospheres synthesized by conventional seeded batch copolymerization. As a previous step for biomedical application, adsorption experiments of bovine albumin on microspheres were carried out under various conditions. The maximum adsorbed amount was obtained in the neighborhood of pH 4.5. Isoelectric point of bovine albumin Is pH 5.0, so experimental result shows that it shifted to acid area. The adsorption Isotherm was obtained, the plateau region was always reached at 2.Og/L (bulk concentration of bovine albumin ) . The effect of the kind and the amount of surface functional group was also examined.p was also examined.

• 대한의용생체공학회:의공학회지
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• 제7권2호
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• pp.183-190
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• 1986

Microspheres are expected to be applied to biomedical areas such as solid-phase immunoassays, drug delivery systems, immunomagnetic cell separation. To synthesize microspheres for biomedical application, "two stage shot growth method" was developed. The uniformity ratio of synthesized microspheres was always smaller than 1.05. And the surface charge density (or the number of ionizable functional groups) of the microspheres synthesized by "two stage shot growth method" was 6~13 times higher than that of the microspheres synthesized by conventional seeded batch copolymerization. As a previous step for biomedical application, adsorption experiments of bovine albumin on microspheres were carried out under various conditions. The maximum adsorbed amount was obtained in the neighborhood of pH 4.5. Isoelectric point of bovine albumin is pH 5.0, so experimental result shows that it shifted to acid area. The adsorption isotherm was obtained, the plateau region was always reached at 2.Og/L (bulk concentration of bovine albumin).The effect of the kind and the amount of surface functional group was also examined.p was also examined.