• Korea-Australia Rheology Journal
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• 제17권3호
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• pp.117-123
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• 2005

Background: Reduced deformability of red blood cells (RBCs) may play an important role on the pathogenesis of chronic vascular complications of diabetes mellitus. However, available techniques for measuring RBC deformability often require washing process after each measurement, which is not optimal for day­to-day clinical use at point of care. The objectives of the present study are to develop a device and to delineate the correlation of impaired RBC deformability with diabetic nephropathy. Methods: We developed a disposable ektacytometry to measure RBC deformability, which adopted a laser diffraction technique and slit rheometry. The essential features of this design are its simplicity (ease of operation and no moving parts) and a disposable element which is in contact with the blood sample. We studied adult diabetic patients divided into three groups according to diabetic complications. Group I comprised 57 diabetic patients with normal renal function. Group II comprised 26 diabetic patients with chronic renal failure (CRF). Group III consisted of 30 diabetic subjects with end-stage renal disease (ESRD) on hemo-dialysis. According to the renal function for the diabetic groups, matched non-diabetic groups were served as control. Results: We found substantially impaired red blood cell deformability in those with normal renal function (group I) compared to non-diabetic control (P = 0.0005). As renal function decreases, an increased impairment in RBC deformability was found. Diabetic patients with chronic renal failure (group II) when compared to non-diabetic controls (CRF) had an apparently greater impairment in RBC deformability (P = 0.07). The non-diabetic cohort (CRF), on the other hand, manifested significant impairment in red blood cell deformability compared to healthy: control (P = 0.0001). Conclusions: The newly developed slit ektacytometer can measure the RBC deformability with ease and accuracy. In addition, progressive impairment in cell deformability is associated with renal function loss in all patients regardless of the presence or absence of diabetes. In diabetic patients, early impairment in RBC deformability appears in patients with normal renal function.

• Journal of Pharmaceutical Investigation
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• 제33권3호
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• pp.187-193
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• 2003

This study was aimed to formulate various phospholipid nanoparticles composed of different surfactants and to evaluate the deformability of the phospholipid vesicles as candidates of useful ultradeformable nanoparticles. In vitro deformability of the phospholipid nanoparticles was studied using an extruder under a certain pressure. The sizes of phospholipid nanoparticles, passed volumes, and concentrations of the phospholipids in suspensions before and after extrusion were measured. The deformability indexes were estimated by using passed volumes, sizes of phospholipid nanoparticles and concentrations of phospholipids. Conventional liposomes, placed under a certain pressure of an extruder, showed no passed volume indicating little deformability. Similar to conventional liposomes, phospholipid nanoparticles containing surfactants such as sodium taurocholate, Myrj 45, or Myrj 53 showed little deformability. In contrast, phospholipid nanoparticles composed of Tween 20, Triton X-100, or sodium deoxycholate showed higher deformability indexes than others. Taken together, the deformability of phospholpid nanoparticles could be significantly affected by the type of surfactants. Moreover, these results suggest that the deformability of phospholipid nanoparticles could be modulated by surfactants.

• Structural Engineering and Mechanics
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• 제40권4호
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• pp.541-562
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• 2011

In the design of earthquake resistant reinforced concrete (RC) structures, both flexural strength and deformability need to be considered. However, in almost all existing RC design codes, the design of flexural strength and deformability of RC beams are separated and independent on each other. Therefore, the pros and cons of using high-performance materials on the flexural performance of RC beams are not revealed. From the theoretical results obtained in a previous study on flexural deformability of RC beams, it is seen that the critical design factors such as degree of reinforcement, concrete/steel yield strength and confining pressure would simultaneously affect the flexural strength and deformability. To study the effects of these factors, the previous theoretical results are presented in various charts plotting flexural strength against deformability. Using these charts, a "concurrent flexural strength and deformability design" that would allow structural engineers to consider simultaneously both strength and deformability requirements is developed. For application in real construction practice where concrete strength is usually prescribed, a simpler method of determining the maximum and minimum limits of degree of reinforcement for a particular pair of strength and deformability demand is proposed. Numerical examples are presented to illustrate the application of both design methods.

• Archives of Pharmacal Research
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• 제11권2호
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• pp.145-148
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• 1988

Effects of brazilin on the blood viscosity and erythrocyte deformability were investigated in alloxan induced diabetic rats. By the treatment to alloxan induced diabetic rats, enhancement of erythrocyte deformability was observed. In the in vitro study on the erythrocyte deformability, brazilin showed statistically significant improving effects on the erythrocyte deformability. At the concentrations of $10^3$ M of brazilin, erythrocyte deformability was compared with those of hematoxylin, pentoxifyline and prednisolone.

• 대한기계학회논문집A
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• 제32권10호
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• pp.844-849
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• 2008

We present a novel cell deformability monitoring chip based on the digitally measured cell lysis rate which is dependent on the areal strain of the cell membrane. This method offers simple cell deformability monitoring by automated high-throughput testing system. We suggest the filter design considering the areal strain imposed on the cell membrane passing through the filter array having gradually increased orifice length. In the experiment using erythrocytes, we characterized the cell deformability in terms of average fracture areal strain which was $0.24{\pm}0.014\;and\;0.21{\pm}0.002$ for normal and chemically treated erythrocytes, respectively. We also verified that the areal strain of 0.15 effectively discriminates the deformability difference of normal and chemically treated erythrocytes, which can be applied to the clinical situation. We compared the lysis rates and their difference for the samples from different donors and found that the present chips can be commonly used without any calibration process. The experimental results demonstrate the simple structure and high performance of the present cell deformability monitoring chips, applicable to simple and cost-effective cell aging process monitoring.

• Earthquakes and Structures
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• 제1권3호
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• pp.269-287
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• 2010

High-strength concrete (HSC) is becoming more popular in the construction of beams and columns of tall buildings because of its higher stiffness and strength-to-weight ratio. However, as HSC is more brittle than normal-strength concrete (NSC), it may adversely affect the flexural ductility and deformability of concrete members. Extended from a series of theoretical study conducted on flexural ductility of concrete beams, the authors would in this paper investigate the effects of some critical factors including the degree of reinforcement, confining pressure, concrete and steel yield strength on the flexural deformability of NSC and HSC beams. The deformability, expressed herein in terms of normalised rotation capacity defined as the product of ultimate curvature and effective depth, is investigated by a parametric study using nonlinear moment-curvature analysis. From the results, it is evident that the deformability of concrete beams increases as the degree of reinforcement decreases and/or confining pressure increases. However, the effects of concrete and steel yield strength are more complicated and dependent on other factors. Quantitative analysis of all these effects on deformability of beams has been carried out and formulas for direct deformability evaluation are developed. Lastly, the proposed formulas are compared with available test results to verify its applicability.

• 약학회지
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• 제31권5호
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• pp.308-314
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• 1987

In cardiovascular disease the flow adaptation of erythrocytes can be affected by reduced shear stresses and metabolic influences on red cell fluidity as a consequence of tissue hypoxia. In addition there are indications that risk factors of cardiovascular diseases are able to decrease the intrinsic red cell deformability. Erythrocyte deformability was studied by the filtration technique of Reid et al. to investigate the relationship between blood pressure chances and erythrocyte deformability. In this experiment normotensive rats, spontaneously and DOCA-salt treated hypertensive rats were used. Erythrocyte deformability was significantly reduced by blood pressure elevation in hypertensive rats but was not fully recovered by normalization of blood pressure after antihypertensive drug treatment. Therefore other factors than blood pressure may be involved in erythrocyte deformability reduction during blood pressure elevation.

• Computers and Concrete
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• 제8권4호
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• pp.445-463
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• 2011

In the design of reinforced concrete (RC) beams, apart from providing adequate strength, it is also necessary to provide a minimum deformability even for beams not located in seismic regions. In most RC design codes, this is achieved by restricting the maximum tension steel ratio or neutral axis depth. However, this empirical deemed-to-satisfy method, which was developed based on beams made of normal-strength concrete (NSC) and normal-strength steel (NSS), would not provide a consistent deformability to beams made of high-strength concrete (HSC) and/or high-strength steel (HSS). More critically, HSC beams would have much lower deformability than that provided previously to NSC beams. To ensure that a consistent deformability is provided to all RC beams, it is proposed herein to set an absolute minimum rotation capacity to all RC beams in the design. Based on this requirement, the respective maximum limits of tension steel ratio and neutral axis depth for different concrete and steel yield strengths are derived based on a formula developed by the authors. Finally for incorporation into design codes, simplified guidelines for designing RC beams having the proposed minimum deformability are developed.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.117-122
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• 2002

Flat Plate structures subjected to lateral load are susceptible to the brittle failure, therefore deformability of plate-column connections should be ensured to resist against earthquake. However, according to previous study, existing experiments overestimate the deformability of connections and current design provision do not accurately explains them. In the present study, parametric study using nonlinear finite element analysis was performed. Based on the numerical results, seismic design method considering the deformability of connections was developed.

• 콘크리트학회논문집
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• 제15권3호
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• pp.482-493
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• 2003

횡하중을 재하받는 플랫 플레이트 구조는 슬래브-기둥의 접합부의 취성적 거동으로 인하여 모멘트골조 구조보다 변형능력이 크게 부족하다. 본 연구에서는 슬래브의 변형능력을 연구하기 위해 비선형 유한요소해석을 이용한 변수연구를 수행하였다. 해석결과, 슬래브의 경간수가 증가함에 따라 슬래브의 변형능력이 크게 감소되는 것으로 나타났으며, 따라서 기둥과 슬래브로 이루어진 축소시험체를 사용하는 기존의 실험연구는 실제 연속슬래브의 변형능력을 과대평가하고 있으며 이에 근거한 현행 설계기준 역시 접합부의 변형능력을 정확히 예측하지 못하고 있다. 해석결과에 근거하여 슬래브의 변형능력을 평가할 수 있는 방법을 개발하였고 기존 실험결과와의 비교를 통해 검증되었다. 제안된 방법에서는 뚫림전단력의 크기 뿐 아니라 접합부의 뚫림전단성능과 형상 단면비, 슬래브 경간수 그리고 슬래브의 초기강성 등 주요 영향변수가 고려되었다.