Browsing by Author "Chen, J. -C."

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A Method for the Non-invasive Assessment of Chest Wall Growth in Pectus Excavatum Patients
(2010-03-01)
Chang, P. -Y.
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Chang, C. -H.
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Lai, J. -Y.
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Chen, J. -C.
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Perng, D. -B.
Introduction: Various scales and measurement methods including X-rays and computed tomography (CT) have been used to quantify the degree of deformity in pectus excavatum. This study describes a non-invasive method for recording the deviation of the anterior chest wall (ACW) in pectus excavatum (PE) patients. Data obtained using this non-invasive method were compared with CT data. Materials and Methods: Twenty-one patients treated at our institutions between June 2008 and February 2009 were enrolled in this study. All patients underwent CT and thermal plastic strip measurement. A thermal plastic strip was positioned and taped to the supine patient's ACW at the skin level from the posterior axillary line, over the depressed sternum, to the contralateral posterior axillary line and used to create a casting of the ACW. Results: The funnel index (FI) was defined as the width of the ACW divided by its height; the concave index (CI) was defined as the breadth of the depressed area of the funnel chest divided by its depth. Pearson's correlation coefficient was used to compare the FI and CI obtained with the thermal plastic strip method and with CT; measurements obtained with both methods were found to correlate well (FI: r(2) = 0.965; CI: r(2) = 0.947). Conclusions: The thermal plastic strip measurement method provides a two-dimensional record of the shape of the anterior chest wall. The measurement can be repeated, does not involve the patient being exposed to radiation, and offers a good longitudinal assessment of chest wall growth in PE patients.
Brain nociceptive imaging in rats using F-18-fluorodeoxyglucose small-animal positron emission tomography
(2008-09-09)
Shih, Y. -Y. I.
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Chiang, Y. -C.
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Chen, J. -C.
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Huang, C. -H.
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Chen, Y. -Y.
Preclinical exploration of pain processing in the brain as well as evaluating pain-relief drugs in small animals embodies the potential biophysical effects in humans. However, it is difficult to measure nociception-related cerebral metabolic changes in vivo, especially in unanesthetized animals. The present study used F-18-fluorodeoxyglucose small-animal positron emission tomography to produce cerebral metabolic maps associated with formalin-induced nociception. Anesthesia was not applied during the uptake period so as to reduce possible confounding effects on pain processing in the brain. The formalin stimulation at the hind paw of rats resulted in significant metabolic increases in the bilateral cingulate cortex, motor cortex, primary somatosensory cortex, secondary somatosensory cortex, insular cortex, visual cortex, caudate putamen, hippocampus, periaqueductal gray, amygdala, thalamus, and hypothalamus. Among the measured areas, clear lateralization was only evident in the primary somatosensory cortex and hypothalamus. In addition, pretreatment with lidocaine (4 mg/kg, i.v.) and morphine (10 mg/kg, i.v.) significantly suppressed formalin-induced cerebral metabolic increases in these areas. The present protocol allowed identification of the brain areas involved in pain processing, and should be useful in further evaluations of the effects of new drugs and preclinical therapies for pain. (C) 2008 IBRO. Published by Elsevier Ltd. All rights reserved.
Controlling droplet bouncing and coalescence with surfactant
(2016-07)
Pan, K. -L.
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Tseng, Y. -H.
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Chen, J. -C.
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Huang, K. -L.
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Wang, C. -H.
The collision between aqueous drops in air typically leads to coalescence after impact. Rebounding of the droplets with similar sizes at atmospheric conditions is not generated, unless with significantly large pressure or high impact parameters exhibiting near-grazing collision. Here we demonstrate experimentally the creation of a non-coalescent regime through addition of a small amount of water-soluble surfactant. We perform a direct simulation to account for the continuum and short-range flow dynamics of the approaching interfaces, as affected by the soluble surfactant. Based on the immersed-boundary formulation, a conservative scheme is developed for solving the coupled surface-bulk convection-diffusion concentration equations, which presents excellent mass preservation in the solvent as well as conservation of total surfactant mass. We show that the Marangoni effect, caused by non-uniform distributions of surfactant on the droplet surface and surface tension, induces stresses that oppose the draining of gas in the interstitial gap, and hence prohibits merging of the interfaces. In such gas-liquid systems, the repulsion caused by the addition of surfactant, as frequently observed in liquid-liquid systems such as emulsions in the form of an electric double-layer force, was found to be too weak to dominate in the attainable range of interfacial separation distances. These results thus identify the key mechanisms governing the impact dynamics of surfactant-coated droplets in air and imply the potential of using a small amount of surfactant to manipulate impact outcomes, for example, to prevent coalescence between droplets or interfaces in gases.