ASSESSMENT OF RED BLOOD CELL DEFORMABILITY BY CENTRIFUGAL SEDIMENTATION

A centrifugal sedimentation method (CSM) is proposed for the assessment of deformability of red blood cells. The method is based on the premise that a red blood cell (RBC) should deform in a centrifugal field due to the variation of the centrifugal acceleration with the distance from the center of rotation. This change in shape of the RBC leads to a change in the rate of sedimentation in the centrifugal field. The rate of sedimentation, which serves as a measure of deformability, is characterized by an apparent sedimentation coefficient (ASC) and its normalized value (NASC), which is calculated by comparison with a control group of normal RBCs. It has been shown that the NASC is sensitive to the speed of rotation, to treatments with glutaraldehyde, diamide, or chlorpromazine, to heat treatment and to osmotic pressure variations.     

板料多道次拉深成形规律和性能的研究

在物理模拟的基础上，研究了板料拉深成形过程中，材料的性能参数和工艺参数对板料成形性能的影响，着重分析了对多道次拉深成形的影响。结果表明，无论是材料性能参数还是材料的工艺参数都对再拉深的影响比对单道次拉深的影响林大得多，但两种参数对多道次拉深的影响过程前后是一致的。同时可以看出，多道次拉深之间是相互影响的，不能割裂开来考虑。     

Deformability properties of timolol-loaded transfersomes based on the extrusion mechanism. Statistical optimization of the process

The purpose of this work was to analyze the deformability properties of different timolol maleate (TM)-loaded transfersomes by extrusion. This was performed because elastic liposomes may contribute to the elevation of amount and rate of drug permeation through the corneal membrane. This paper describes the optimization of a transfersome formulation by use of Taguchi orthogonal experimental design and two different statistical analysis approaches were utilized. The amount of cholesterol (F1), the amount of edge-activator (F2), the distribution of the drug into the vesicle (F3), the addition of stearylamine (F4) and the type of edge-activator (F5) were selected as causal factors. The deformability index, the phosphorous recovery, the vesicle size, the polydispersity index, the zeta potential and percentage of drug entrapped were fixed as the dependent variables and these responses were evaluated for each formulation. Two different statistical analysis approaches were applied. The better statistical approach was determined by comparing their prediction errors, where regression analysis provided better optimized responses than marginal means. From the study, an optimized formulation of TM-loaded transfersomes was prepared and obtained for the proposed ophthalmic delivery for the treatment of open angle glaucoma. It was found that the lipid to surfactant ratio and type of surfactant are the main key factors for determining the flexibility of the bilayer of transfersomes. From in vitro permeation studies, we can conclude that TM-loaded transfersomes may enhance the corneal transmittance and improve the bioavailability of conventional TM delivery.     

新型Cr12V钢在不同温度下的变形性能

对高碳高铬系列中的新钢种Cr12V钢在不同温度和不同速度下作一系列镦粗试验,并得出相应的变形曲线和基本理论的关系式。通过试验证明,所得结论准确,为该新钢种的锻造规范提供了理论和实践依据。     

Bonding wire characterization using automatic deformability measurement

A promising way to control underpad chip damage in IC packaging caused by wire bonding forces would be to use new wire chemistries that produce softer free-air balls (FABs). The number of new wire types that can be tested is limited by the available resources. The conventional FAB hardness characterization method is the microindentation test, a labour intensive and off-line task requiring cross-sectioning of a large number of samples. To accelerate FAB hardness characterization, an innovative on-line method is studied and presented here, enabling the fast comparison of different wire types. Collection of data from an instrumented wire bonder allows comparison of the deformability, i.e. the average amount of FAB deformation under a defined load. Increased deformability implies a softer FAB. The influences have been studied of changes in capillary, bonding substrate metallization and substrate temperature on the results obtained. It is found that these influences need to be held constant during a comparison study.     

FRP-strengthened RC slabs anchored with FRP anchors

An abundance of tests over the last two decades has shown the bending capacity of flexural members such as reinforced concrete (RC) beams and slabs to be enhanced by the bonding of fibre-reinforced polymer (FRP) composites to their tension face. The propensity of the FRP to debond, however, limits its effectiveness. Different types of anchorages have therefore been investigated in order to delay or even prevent debonding. The so-called FRP anchor, which is made from rolled fibre sheets or bundles of lose fibres, is particularly suitable for anchoring FRP composites to a variety of structural element shapes. Studies that assess the effectiveness of FRP anchors in anchoring FRP strengthening in flexural members is, however, limited. This paper in turn reports a series of tests on one-way spanning simply supported RC slabs which have been strengthened in flexure with tension face bonded FRP composites and anchored with different arrangements of FRP anchors. The load-deflection responses of all slab tests are plotted, in addition to selected strain results. The behaviours of the specimens including the failure modes are also discussed. The greatest enhancement in load and deflection experienced by the six slabs strengthened with FRP plates and anchored with FRP anchors was 30% and 110%, respectively, over the unanchored FRP-strengthened control slab. The paper also discusses the strategic placement of FRP anchors for optimal strength and deflection enhancement in FRP-strengthened RC slabs.     

Applicability of the geological strength index (GSI) classification for very weak and sheared rock masses. The case of the Athens Schist Formation

 The Athens Schist Formation includes a wide variety of metasedimentary rocks, varying from strong or medium strong rocks such as sericite metasandstone, limestone, greywacke, sericite schist through to weak rocks such as metasiltstone, clayey and silty shale and phyllite. The overall rock mass is highly heterogeneous and anisotropic owing to the combined effect of advanced weathering and severe tectonic stressing that gave rise to intense folding and shearing followed by extensional faulting, which resulted in highly weathered rock masses and numerous shear and/or mylonite zones with distinct downgraded engineering properties. This paper is focused on the applicability of the GSI classification system to these highly heterogeneous rock masses and proposes an extension of the GSI system to account for the foliated or laminated weak rocks in the lower range of its applicability. Received: 5 March 1998 · Accepted: 13 July 1998     

Deformability of red blood cells: A determinant of blood viscosity

The suspension of hardened red blood cells (RBCs) differs from the suspension of normal RBCs with respect to their rheological behavior. The present study investigated the effect of deformability of RBCs on blood viscosity. RBC deformability and blood viscosity were measured with a recently developed slit-flow laser-diffractometer and the pressure-scanning capillary viscometer, respectively. At the same level of cell concentration, the viscosity of the hardened RBC suspension is higher than that of the normal RBCs suspension. An increase in cell percentage for hardened RBCs shows the significant increase in the level of blood viscosity compared to the normal RBCs. In addition, it was found that RBC deformability played an important role in reducing viscosity at low shear rates as well as high shear rates. These results present the evidence for the effect of RBC deformability on blood viscosity using newly developed methods, which can be used in early diagnosis of the cardiovascular diseases.     

Effect of electronic flame off parameters on copper bonding wire: Free-air ball deformability, heat affected zone length, heat affected zone breaking force

Cu bonding wire is more and more used for interconnections to integrated circuits (ICs) to reduce cost and increase performance compared to Au wire. To eliminate underpad damage for Cu wire applications, it is worthwhile to reduce the hardness of the free-air ball (FAB). Short heat affected zone (HAZ) and high HAZ breaking load are often required for advanced microelectronics packaging in order to decrease the loop height and thereby the package thickness.Online measurements of deformability and HAZ breaking force at temperatures close to the bonding temperature of 220 °C are new tools used in this study to evaluate the effects of electronic flame off (EFO) current and firing time on the Cu FAB deformability and the HAZ length and tensile strength. FABs with 50 μm diameter formed from a 25 μm diameter Cu wire with a breaking load of 118.6 mN were used. EFO currents and firing times ranged from 40 to 250 mA and 0.11 to 0.90 ms, respectively. Average FAB deformability factors, HAZ breaking forces, and HAZ lengths were in the rounded ranges of 36.64–44.09% (with a deformation force of 0.60 N), 107.7–116.8 mN, and 167–215 μm, respectively. When produced with 250 mA current during 0.11 ms, the FABs are 7.01–7.89% more deformable than when produced with 45 mA during 0.9 ms, the HAZ breaking force is 7.53–9.37% higher, and the HAZ length is 7–90 μm shorter.     

Models for normal fracture deformation under compressive loading

A new semi-empirical model that can be used to predict fracture deformation behavior under normal compressive loading is presented. The development of a simple exponential model is presented first after which a modified and more general exponential model, with an additional degree of freedom in the model parameters, is obtained. The simple and the modified exponential models are then compared to available fracture closure models, namely the empirical Barton–Bandis hyperbolic model, and a power-law model based on Hertzian contact theory, to determine how good they fit the results of fracture closure experiments under monotonically increasing normal compressive loading. A new parameter called the half-closure stress, σ_1/2, is introduced and is used, in addition to the maximum fracture closure, Δv_m, in the model fitting procedures for the Barton–Bandis and the simple exponential model. The half-closure stress is shown to be related to the initial normal stiffness, K_ni, used in the original Barton–Bandis model. An additional parameter, n, is used in fitting the modified exponential model to the experimental data. Of the models presented herein, the modified exponential model was found to provide the best fit to the experimental data, for the same values of σ_1/2 and Δv_m, over the entire range of compressive stresses. The power-law model based on Hertzian contact theory was found to be unsuitable for predicting normal fracture deformation behavior.