Kazuishi Sato

Correlation between tensile properties and network draw ratio for poly(ethylene terephthalate) fibers with wide range of molecular orientation and crystallinity

Poly(ethylene terephthalate) (PET) fibers with wide range of molecular orientation and crystallinity were prepared by the cold drawing of melt-spun yarns in a temperature-controlled water bath and the subsequent annealing for these samples. For all samples, the true stress-strain curves can be principally superimposed to a master curve which corresponds to the stress-strain curve for the original nonoriented amorphous yarn and it was confirmed that the original (intrinsic) network structure is not affected by molecular orientation and crystallinity significantly. Tensile properties of these fibers were studied systematically in terms of the network draw ratio which was determined as a shift factor in the matching process of a true stress-strain curve to the master curve. Consideration of the tensile drawing behavior has shown that the network draw ratio, which is defined as an extension of unique intrinsic network structure, has direct correlation with mechanical properties including the yield and breaking behaviors. When the network draw ratio is taken into consideration, PET fiber, even if it has crystallinity or molecular orientation, has appeared to behave in the manner of an almost ideal rubber during the tensile testing carried out as cold drawing.

Blood-mimicking fluid using glycols aqueous solution and their physical properties

We present blood-mimicking fluids (BMFs) for the Doppler test object of medical ultrasound diagnostic instruments. Each of the acoustic velocity, density, and viscosity defined in the International Electrotechnical Commission (IEC) standard is given as a constant value. However, the viscosity of human blood depends greatly on the shear rate of the blood. In accurate studies using a specified flow phantom, therefore, the BMFs with the appropriate viscosity are required. To formulate fluids with the viscosity ranging from 4 to 30 mPas, we have developed a new fluid made of glycols and water-soluble silicone oil. We have used ethylene glycol, diethylene glycol, triechylene glycol, and poly(ethylene glycol) for the fluid. The glycols have different viscosities depending on their molecular weight and their acoustic velocity and density are almost the same. By selecting the glycol with the optimum molecular weight, the viscosity of the fluid could be set at the desired value and the acoustic properties of this fluid satisfied the values of the acoustic velocity and density defined by the IEC standard.

Blood-mimicking fluid for the Doppler test objects of medical diagnostic instruments

We present a blood-mimicking fluid for the Doppler test object of medical diagnostic instruments. Accurate measurement in a flow Doppler test requires a blood-mimicking fluid (BMF) that has the acoustic velocity, density, attenuation coefficient, and viscosity defined in the International Electrotechnical Commission (IEC) standard, and furthermore, they must be stable over time. To formulate a fluid with the desired density and acoustic velocity, we have developed a new fluid made of glycerine and water soluble silicone oil. The BMF is dispersed polystyrene particles as scatters in the new fluid. The density of the liquid can be adjusted to maintain the density of the liquid at the same value as that of the polystyrene particles, thus ensuring neutral buoyancy of the particles. The blood-mimicking fluid was stable overlong term, and the acoustic velocity, density, attenuation coefficient, and viscosity of the fluid meet the specific values.

A new tissue-mimicking material for phantoms

We present a tissue-mimicking material for the phantom of medical diagnostic instruments. Accurate testing of an instrument by phantoms requires a tissue-mimicking material that has the acoustic velocity, density, and attenuation defined in the International Electrotechnical Commission (IEC) standard, and furthermore the tissue-mimicking material must be stable over time. To achieve the material with the desired acoustic velocity, density, and attenuation, we have developed a new permanent gel with any arbitrary acoustic velocity and little attenuation. The gel originates a swollen segmented polyurethane gel with tetraethylene glycol dimethyl ether and 1-Butyl-3-methylimdazolium thiocyanate as medium. The developed tissue-mimicking material was prepared from the permanent swollen segmented polyurethane gel with dispersed poly(methyl methacrylate) particles.

Blood-Mimicking Fluid for Testing Ultrasonic Diagnostic Instrument

We present a blood-mimicking fluid (BMF) for the Doppler test object of medical diagnostic instruments. Accurate measurement in a flow Doppler test requires a BMF that has the acoustic velocity and density defined in the International Electrotechnical Commission (IEC) standard, and furthermore, they must be stable over time. To formulate a fluid with the desired density and acoustic velocity, we have developed a new fluid made of glycerine and water-soluble silicone oil. The new BMF includes dispersed polystyrene particles as scatterers. The density of the liquid can be adjusted to maintain it at the same value as that of the polystyrene particles, thus ensuring neutral buoyancy of the particles. The MBF was stable over a period of 2 weeks, during which the density and acoustic velocity did not change.