Key Engineering Materials Vols. 321-323

Abstract: This study addressed the effect of balance control problems on the high-heeled women. The specific purposes of this study are to quantify the displacements and velocities of center-of-pressure (COP) of a body during waist pulling perturbation and to compare the differences between the bare-feet and the high-heeled. Another purpose of the study is to identify the effects of a high-heeled posture on electromyography (EMG) activities and muscle fatigue. We used a waist pulling system which has three different magnitudes to sway the subjects. The COP displacement of a high-heeled posture was about twice as much as that of bare-feet posture. Also the COP velocity of a high-heeled posture became about twice as much as that of bare-feet posture. Muscle fatigue could be identified by the shift of the median frequency (MF) of the EMG power spectrum toward lower frequencies. Median frequency of the EMG power spectrum from tibialis anterior was reduced more rapidly during high-heeled situation than during bare-feet situation. COP kinematics and muscle fatigue analysis in postural balance researches are considered to provide useful information in understanding the balance control mechanism of women’s high-heeled posture.

Abstract: Harmonic image (HI) has been proposed to be promising for visualizing lesions produced by therapeutic high intensity focused ultrasound (HIFU). The study characterizes harmonics generated from the bubble cavitating at the focal region of a therapeutic HIFU field in response to a typical diagnostic ultrasound. Based on Gilmore model, it was simulated the nonlinear dynamics of the bubble being resonated at 1 MHz of the therapeutic ultrasound and driven by a typical 3.5 MHz diagnostic pulse. It was shown that harmonic generation increased with MI in a sigmoid pattern where the rapid and transient changes occurred between 0.5 and 2 in MI. For whole ranges of MI (less than 8), the sub-harmonic was the predominant in magnitudes over other harmonic bands. This reveals that, if HI is considered for improving the detection of focal legion highly cavitating caused by a HIFU field, the sub-harmonic component would be a preferred parameter rather than the 2nd harmonic which has been commonly used in current harmonic imaging.

Abstract: Investigation of the bone mineral density (BMD), microstructural and mechanical properties in the Otsuka Long Evans Tokushima Fatty (OLETF) and Otsuka Long Evans Tokushima Fatty (LETO) rats were performed. The BMD and microstructural analyses were carried out using PIXI-mus and non-invasive highresolution micro-computed tomography (micro-CT) system. The mechanical properties analyses were determined by finite element analysis based on micro-images. The BMD was significantly larger in LETO rat than in OLETF rat. The microstructural and mechanical properties were deteriorated and decreased in OLETF rat. The results showed that bone strength is decreased in OLETF in spite of high body weight.

Abstract: The study considers an ultrasonic characterization on the thermal distribution in vicinity for a cylindrical thermal lesion formed in a biological tissue. The cylindrical heat source is made of a standard nichrome wire with the diameter of 1 mm. The wire was inserted inside a pork muscle housed in a cuboidal container made of perspex. The heat is conducted radially outwards from the wire to the surrounding tissue. Thermal distribution near the heated wire was predicted by numerically solving a bioheat transfer function using FemLab (Comsol, Inc.). As the wire temperature was raised from the environmental temperature 20 °C to more than 80 °C in steps of 5 °C, ultrasonic B-scan images were acquired at each temperature. We assessed the feasibility of detecting the lesion boundary using changes in echogenicity, changes in centroid frequency due to attenuation, tissue moving characteristics resulting from changes in the speed of sound, and elastograms. These observations will be of use in improving ultrasonic monitoring and guiding in HIFU surgery and thermo-therapeutic process in general.

Abstract: Mandibular first premolars in superlative state were scanned by a Micro-CT. Data were obtained from the scanned 2-D images, and reconstructed into 3-D models for FEA, at which point stress distribution of the inner and outer part of the tooth were shown. It was found that when compared with the teeth data used as a standard by G. V. Black, the aspect of the external morphology of the teeth is comparatively small regardless of gender. Also, differences exist between the Micro-CT data and G. V. Black’s data. This study also presents the internal morphological data that was not shown in G. V. Black’s data. The dentin size is larger than the enamel size in both males and females in the case of the internal morphological data. It is found that the stress was concentrated on the cervical line, and the stress varied around the boundary between dentin and enamel within the teeth. It is also revealed that the stress varied at the boundary surface between dentin and pulp. The results using a Micro-CT and stress analysis may reveal the cause of the abfraction, and bring up a guideline for endodontic treatment.

Abstract: Frequent outbreaks of foodborne illness have been increasing the need for simple, rapid and sensitive methods to detect foodborne pathogens. Conventional methods for pathogen detection and identification are labor-intensive and take days to complete. Some immunological rapid assays are developed, but these assays still require prolonged enrichment steps. Biosensors have shown great potential for the rapid detection of foodborne pathogens. Among the biosensors, fiber-optic methods have much potential because they can be very sensitive and simple to operate. Fiber-optic biosensors typically use a light transmittable, tapered fiber to send excitation laser light to the detection surface and receive emitted fluorescent light. The fluorescent light excited by an evanescent wave generated by the laser is quantitatively related to fluorophor-labeled biomolecules immobilized on the fiber surface. A portable and automated fiber-optic biosensor, RAPTOR (Research International, Monroe, WA), was used to detect Salmonella enteritidis in food samples. A binding inhibition assay based on the biosensor was developed to detect the bacteria in hot dog samples. The biosensor and the binding inhibition assay could detect 104 cfu/ml of bacteria in less than 10 min of assay time.

Abstract: The changes in the Helmholtz resonant frequency and acoustic absorption during the rise of bread dough were investigated. The dough volume predicted by using the Helmholtz resonant frequency increased in the fermentation process; however, it was below the true volume. The apparent acoustic absorption coefficients determined by sound intensities increased when the bread dough rose. The acoustic absorption caused by the pores in the dough might decrease the resonant frequency. The increase in the dough volume should change the shape of a part of the power spectrum curve besides the spectrum peak. In order to detect such a small change, the difference spectrum between two spectra obtained at intervals of 1365.34 ms was used. The values predicted based on the frequency of the zero crossover point, such as the isosbestic point, agreed with the dough volume.

Abstract: Fluorescence techniques have demonstrated great potential for detection of the presence of fecal and other biological substances that can harbor pathogens. We used a recently developed laser-induced fluorescence imaging system (LIFIS) to demonstrate the potential use of fluorescence techniques for detection of a range of diluted poultry feces from various sections of the digestive tract, including gizzard, duodenum, small intestine, ceca, and colon, on processing plant equipment. The use of the LIFIS allowed tunable excitation in the visible with selection of emission wavebands for multispectral imaging. Thus, both fluorescence excitation and emission parameters can be optimized (e.g., 415 nm excitation, and 580 and 630 nm emission bands). The results showed that 1:5 and 1:10 diluted feces samples could be detected with 100% detection rates at the 580 and 630 nm emission bands regardless of feces types. Detection rates for 1:50 and 1:100 diluted samples at the 580-nm band were 96.0 and 89.3%, respectively, and those at the 630-nm band were 94.7 and 84.0%, respectively. Even minute amounts of fecal matter on processing plant equipment surfaces, not clearly visible to the human eye, could be detected.

Abstract: A PC controlled food contaminant detection system for practical use was designed and constructed. The system we have developed is the High-Tc SQUID based system, which is covered with waterproof stainless steel plates and acceptable to HACCP (Hazard Analysis and Critical Control Point) program. The outer dimension of the system is 1500L mm x 477W mm x 1445H mm and the acceptable object size is 200W mm x 80H mm. This system employed a double-layered permeable metallic shield with thickness of 1 mm as a magnetically shielded box. The distribution of the magnetic field in the box was simulated by FEM; the gap between each shield layer was optimized before fabrication. Then the shielding factor of 732 in Z-component was achieved. This value is good enough to operate the system in a factory. As a result, we successfully detected a steel ball as small as 0.3 mm in diameter with a distance of 75 mm.

Abstract: Fiber-optic biosensor uses light transmittable tapered fiber to send excitation laser light and receive emitted fluorescent light. The fluorescent light excited by an evanescent wave generated by the laser is quantitatively related to biomolecules immobilized on the fiber surface [1]. An automated fiber-optic biosensor based detection method for Listeria monocytogenes was developed in this research. Detections of Listeria monocytogenes in hotdog sample were performed to evaluate the method. By using the detection method with automated fiber-optic biosensor, 5.4×107 cfu/ml of Listeria monocytogenes was able to detect.