• International Journal of Vascular Biomedical Engineering
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• 제4권1호
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• pp.17-26
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• 2006

Diabetes mellitus (DM) is a metabolic disorder, characterized by varying or persistent hyperglycemia, which induces several changes in the erythrocyte membrane and its cytoplasm, leading to alteration in the deformability. Techniques applied to measure this are based on filtration of erythrocyte suspension through a membrane and to obtain diffraction pattern under sheared conditions. Ektacytometry requiring less quantity of blood with disposable flow chamber used to measure the deformability of erythrocytes obtained from patients with diabetes and also associated with nephropathy and retinopathy. A decreasing trend of deformability in these patients is observed. The shape parameter form factor, as determined by image processing procedure, increases with the increased of blood glucose levels and shows a pattern similar to filtration time of erythrocyte suspensions through cellulose membranes. Further work is suggested to detect micro-level changes in cell membrane in diabetic patients

• International Journal of Vascular Biomedical Engineering
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• 제4권2호
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• pp.7-12
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• 2006

The present study investigated the effects of the osmotic environment on the rheological properties of erythrocytes and their suspensions. In an iso-osmotic medium, erythrocytes forming a biconcave discocyte under resting conditions, exhibited high deformability. In a low-osmotic medium, the deformability of erythrocytes, which swelled and exhibited a spherical shape, significantly decreased at a high shear stress and the high-shear viscosity of the cell suspension was slightly higher than that of normal blood. Hyper-osmotic stress, however, which caused to form echinocytes, decreased cell deformability but exhibited smaller viscosity in low shear rates than iso-osmotic blood viscosity. These results showed a close relation with the aggregability measurements, in that hypertonic blood showed lower aggregability than the hypotonic and isotonic RBC suspensions. These findings indicate that the physicochemical environment has a strong influence on the rheological properties of the erythrocyte and its suspensions.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1505-1509
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• 2004

The suspension of hardened red blood cells (RBCs) differs from the suspension of normal RBCs with respect to their rheological behavior. The deformability of normal and hardened RBCs (obtained by heating blood at $49^{\circ}C$ or by incubating RBCs in a solution of hydrogen peroxide) was measured with a slit diffractometer and RBC suspension viscosity was measured with a rotational viscometer. The peroxide-treated RBCs showed a significant decrease of the deformability and their suspension viscosity increased over a range of shear rates. The suspension viscosity of the heated RBCs, however, where the deformability is even lower than that of the peroxide-treated RBCs, was slightly higher than that of the normal RBC suspension in the high shear rates. The present study found that not all rigid cells cause an increase of blood viscosity at high shear rate, and therefore that decreased membrane deformability is not predictive of high-shear blood viscosity.

• 한국재료학회지
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• 제23권8호
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• pp.423-429
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• 2013

Recently, steel structures have increasingly been required to have sufficient deformability because they are subjected to progressive or abrupt displacement arising from structure loading itself, earthquake, and ground movement in their service environment. In this study, high-strength low-carbon bainitic steel specimens with enhanced deformability were fabricated by varying thermo-mechanical control process conditions consisting of controlled rolling and accelerated cooling, and then tensile and Charpy V-notch impact tests were conducted to investigate the correlation between microstructure and mechanical properties such as strength, deformability, and low-temperature toughness. Low-temperature transformation phases, i.e. granular bainite (GB), degenerate upper bainite(DUB), lower bainite(LB) and lath martensite(LM), together with fine polygonal ferrite(PF) were well developed, and the microstructural evolution was more critically affected by start and finish cooling temperatures than by finish rolling temperature. The steel specimens start-cooled at higher temperature had the best combination of strength and deformability because of the appropriate mixture of fine PF and low-temperature transformation phases such as GB, DUB, and LB/LM. On the other hand, the steel specimens start-cooled at lower temperature and finish-cooled at higher temperature exhibited a good low-temperature toughness because the interphase boundaries between the low-temperature transformation phases and/or PF act as beneficial barriers to cleavage crack propagation.

• Archives of Pharmacal Research
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• 제11권2호
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• pp.149-154
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• 1988

Impaired erythrocyte deformability was considered to paly an important role in microcirculatory disturbances. We recently confirmed that the brazilin, the main active principle of Caesalpinia sappan, enhanced activity of erythrocyte deformability and reduced blood viscosity. In this study, we examined the effects of brazilin on three biochemical parameters (ATP, 2, 3-diphosphoglycerate, and calcium) which influenced erythrocyte deformability. Treatment with barzilin increased erythrocyte deformability and ATP concentrations in streptozotocin-induced diabetic rats. Concentrations of 2, 3-diphosphoglycerate and calcium in diabetic rats following brazilin administration were decreased significantly compared to those of diabetic control rats. The results suggest that brazilin have a potential effect to improve rheological abnormalities in diabetes.

• 한국가시화정보학회지
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• 제18권3호
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• pp.103-108
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• 2020

RBC (red blood cell) deformability is one of factors inducing blood shear thinning effect. Reduction of RBC deformability increases blood viscosity in high shear region. In this study, 3D printed chip with proper distribution of wall shear rate (WSR) was proposed to measure RBC deformability of blood samples. To fabricate 3D printed chip, the design of 3D printed chip determined through numerical simulation was modified based on the resolution of the 3D printer. For the estimation of pressure drop in the 3D printed chip, two bypass outlets with low and high WSR are exposed to atmospheric pressure through the needles. By positioning the outlet of needles in the gravity direction, the formation of droplets at bypass outlets can be captured by smartphone. Through image processing and fast Fourier transform (FFT) analysis, the frequency of droplet formation was analyzed. Since the frequency of droplet formation is related with the pressure at bypass, high pressure drop caused by reduction of RBC deformability can be estimated by monitoring the formation of blood droplets using the smartphone.

• 터널과지하공간
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• 제31권1호
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• pp.66-81
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• 2021

본 연구는 삼차원 절리텐서 파라미터와 DFN(discrete fracture network) 블록의 변형특성 간의 상관성 분석을 수행하여 절리텐서의 방향성분 및 일차불변량이 절리성 암반의 변형계수 및 전단탄성계수에 미치는 영향을 평가하였다. 확정적 방향성을 갖는 1~2개의 절리군을 사용하여 절리의 빈도 및 길이분포의 변화에 따라 생성한 총 224개의 DFN 블록에 대하여 절리텐서 파라미터가 산정되었다. 또한, 정육면체 DFN 블록에 대하여 개별요소법을 활용하여 서로 직교하는 세 방향으로 변형특성이 추정되었다. 절리텐서의 일차불변량이 증가할수록 변형계수 및 전단탄성계수는 대체로 저감되는 양상을 나타내지만, 감소폭이 줄어들어 일차불변량이 특정 기준값을 상회하면 변형계수 및 전단탄성계수는 거의 일정한 값을 유지하였다. 삼차원 DFN 블록에 대한 지향적 변형특성은 대응하는 방향의 절리텐서성분과 멱함수의 강한 상관관계를 도출하였다.

• 대한한방내과학회지
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• 제31권3호
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• pp.578-585
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• 2010

Objectives : Coldness of hands and feet has been regarded to be associated with blood circulation. This study was performed to assess the correlation between erythrocyte deformability and coldness of hands and feet. Methods : 145 patients who had taken an erythrocyte deformability test were selected for this study among hospitalized patients within 4 weeks after their cerebral infarction at the Internal Medical Department at Kyunghee Oriental Medical Center from August 2008 to August 2009. We divided the selected patients into two groups, with and without of coldness of hands and feet groups. The two groups were compared on risk factors for atherosclerosis and examined for variables including erythrocyte deformability. Results : 1. On demographic variables of the patients, only body mass index was significantly lower in the coldness of hands and feet group than the control group. There was no significant difference of the rate of hypertension, diabetes mellitus, hyperlipidemia, ischemic heart disease, smoking, drinking and carotid artery stenosis between the two groups. 2. According to blood test, the coldness of hands and feet group showed significantly lower erythrocyte deformability index than the control group. 3. Body mass index and erythrocyte deformability index showed a close relationship with coldness of hands and feet in multivariate analysis. Conclusions : The correlation between the erythrocyte deformability and coldness of hands and feet in cerebral infarction patients were decreased erythrocyte deformability participated in the mechanism of coldness of hands and feet.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.261-264
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• 2006

Deformability of RC members in shear after flexural yielding is limited and controlled by governing failure modes and material strength. Shear strength of members in D-regions has been explained by a direct load path (direct strut or arch action) and indirect load path (fan action or truss action). Indirect load path including truss action and fan action rely on bond along tension ties. Generally, superposition of two actions results in total shear strength when shear failure modes control. The ultimate deformation depends on controlling failure modes and thereby, their force transfer patterns. Proposed models are capable of explaining of limited deformability of RC members in D-regions.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2791-2796
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• 2007

In their long journey through the cardiovascular circuit, erythrocytes are coerced to shape transform and assume different shapes on account of varying flow conditions in different blood vessels. The present work was aimed to visualize these erythrocyte shape transformations by an invitro microcirculatory model, and assess multi-shape erythrocyte deformability. The model uses an in-house fabricated, inexpensive disposable micro flow channel to mimic certain invivo conditions and a fast frame video microscopic system for imaging the shape changes in erythrocytes. Results show the multi-shape transformation of erythrocyte christened as discoidal shape, the asymmetrically deformed 'hat' and 'bullet-like' shapes, and the axially deformed 'slipper' and 'spindle-like' shapes. Specific erythrocyte showed the shape transition and transformation while passing through the observed window. The obtained erythrocyte shapes very analyzed for deformability index using image processing techniques that varied significantly (p <0.001) for different shapes as compared with the resting shape.