No abstract

When quantifying mechanical properties of blood samples flowing in closed fluidic circuits, blood samples are collected at specific intervals. Centrifugal separation is considered as a required procedure for preparing blood samples. However, the use of centrifuge is associated with several issues, including the potential for red blood cell (RBC) lysis, clotting activation, and RBC adhesions in the tube. In this study, an ultrasonic transducer is employed to separate RBCs or diluent from blood sample. The ultrasonic radiation force is much smaller than the centrifugal force acting in centrifuge, it can avoid critical issues occurring under centrifuge. Then, the RBC aggregation and blood viscosity of the blood sample are obtained using the microfluidic technique. According to the numerical results, ultrasonic transducers exhibited a maximum quality factor at an excitation frequency of 2.1 MHz. Periodic pattern of acoustic pressure fields were visualized experimentally as a column mode. The half wavelength obtained was as 0.5 λ = 0.378 ± 0.07 mm. The experimental results agreed with the analytical estimation sufficiently. An acoustic power of 2 W was selected carefully for separating RBCs or diluent from various blood samples (i.e., Hct = 20% ~ 50%; diluent: plasma, 1x phosphate-buffered saline (PBS), and dextran solution). The present method was employed to separate fixed blood samples which tended to stack inside the tube while using the centrifuge. Fixed RBCs were collected easily with an ultrasonic transducer. After various fixed blood samples with different base solutions (i.e., glutaraldehyde solution, 1x PBS, and dextran solution) were prepared using the present method, RBC aggregation and the viscosity of the blood sample are successfully obtained. In the near future, the present method will be integrated into ex vivo or in vitro fluidic circuit for measuring multiple mechanical properties of blood samples for a certain longer period.

Social cost of insomnia in modern society is gradually increasing. Due to various social phenomena and lifestyles that take away the opportunity of good quality of sleep, problems of insomnia cannot be easily figured out. Prescription of sleeping pills for insomnia patients can cause other inconveniences due to their side effects beyond their intended purposes. On the other hand, Passiflora incarnata L. (PI) has been widely used in South America for several centuries, showing effectiveness for sleep, sedation, anxiety, and so on in the civilian population. However, reports on the treatment efficacy of this herbal medicinal plant for insomnia patients through standardization as a sleeping agent have been very rare. Therefore, we obtained leaves and fruits of PI (8:2 by weight) as powder to prepare an extract. It was then applied to C6 rat glioma cells to quantitate mRNA expression levels of GABA receptors. Its sleep‐inducing effect was investigated using experimental animals. PI extract (6 μg/ml) significantly decreased GABA receptors at 6 hr after treatment. Immobility time and palpebral closing time were significantly increased after single (500 mg/kg) or repeated (250 mg/kg) oral administration. In addition, blood melatonin levels were significantly increased in PI extract‐treated animals after both single and repeated administrations. These results were confirmed through several repeated experiments. Taken together, these results confirmed that PI extract had significant sleep‐inducing effects in cells and animals, suggesting that PI extract might have potential for treating human insomnia.

The dispersion characteristics of the nano-sized Y 2 O 3 powders in molten aluminum were investigated from the viewpoint of changes in microstructure and mechanical property as a function of oxide contents. As the solidification structure, the oxide nanoparticles dispersed in the columnar crystal was mainly segregated on the grain boundary, whereas the oxide nanoparticles dispersed in the equiaxed crystal was uniformly dispersed on both grain boundary and inside the crystal. The most uniform dispersion of oxide nanoparticles was observed at Y 2 O 3 content of 2 mass%. As Y 2 O 3 content of 3 mass%, the size of oxide nanoparticles in metal matrix increased due to the particle aggregation, as confirmed by SEM analysis. Moreover, it was found that the mechanical properties such as hardness and tensile strength were improved at Y 2 O 3 content of 2 mass%, indicating the well-dispersion of nano-sized Y 2 O 3 powders in cast aluminum. The hardness was increased by 1.2 times up to 57 H V and tensile strength was increased by 1.55 times up to 80 MPa, compared with the case of pure aluminum. However, at Y 2 O 3 content of 3.0 mass%, tensile strength was sharply decreased by 0.6 times due to aggregation of oxide nanoparticles, while the hardness was increased to 57 H V , which is the same as the case of Y 2 O 3 content of 2.0 mass%.

Implant surgery is generally accepted as the good technique to replace the teeth completely. Development of CT(Computerized Tomography) and 3D visualization technique help to make the treatment plan and the surgical navigation assists the dentist during the intra-operative procedure. Although the navigation technique facilitates the positioning, the image guided adjustment of the angle cannot be attained easily in the dental surgery. In the paper, design and simulation of assistmanipulator for implant surgery are studied. Angulation device performs a task by cooperative manipulation. The force/torque sensor is attached to the tool and specifically designed for surgeon's input. Data acquisition board, LabVIEW software and ATI force/torque sensor are used for smooth and accurate sensing. The double parallelogram mechanism can provide a fixed entry point during the surgery, enhance the safety and quality, and give facilities for surgeons. The 3D visualization program of manipulator is developed by LabVIEW.I.