The Effect of Phonetic Training on the Perception and the Production of L1-Related Difficult Sounds in ESL

A considerable amount of research has been conducted on the influence of first languages’ phonological features in pronunciation of a second language. While it has been accepted that pronunciation is one of the most significant aspects in the acquisition of a second language, many studies have not considered whether explicit phonetic training in pronunciation would help English as Second language Learners to improve their pronunciation on particular English sounds that can be confused due to L1 influence. The present study will explore whether Korean ESL learners are able to perceive the particular pairs of the different phonetic sounds (i.e., /p/-/f/, /b/-/v/, /s/-/ ʃ/ , and /r/-/l/) and whether giving Korean ESL learners explicit phonetic training in pronunciation would lead to more accurate perception and production on the targets sounds. A group of twelve Korean ESL learners took a pre/post-test to evaluate the effectiveness of the treatment, an explicit phonetic training. The phonetics class taught the phonological features of the particular pairs of L1-related difficult sounds of English for two hours by emphasizing the characteristics of each sound in terms of place of articulation, manner of articulation, and voicing. The results showed that there is no significant difference between pre-test and post-test. Thus, the explicit phonetic training was not an effective means of improving pronunciation of ESL learners

Synthesis of Mesostructured Conducting Polymer-Carbon Nanocomposites and Their Electrochemical Performance

A conducting polymer layer was introduced into the pore surface of mesoporous carbon via vapor infiltration of a monomer and subsequent chemical oxidative polymerization. The polypyrrole, conducting polymer has attracted considerable attention due to the high electrical conductivity and stability under ambient conditions. The mesoporous carbon-polypyrrole nanocomposite exhibited the retained porous structure, such as mesoporous carbon with a three-dimensionally connected pore system after intercalation of the polypyrrole layer. In addition, the controllable addition of pyrrole monomer can provide the mesoporous carbon-polypyrrole nanocomposites with a tunable amount of polypyrrole and texture property. The polypyrrole layer improved the electrode performance in the electrochemical double layer capacitor. This improved electrochemical performance was attributed to the high surface area, open pore system with three-dimensionally interconnected mesopores, and reversible redox behavior of the conducting polypyrrole. Furthermore, the correlation between the amount of polypyrrole and capacitance was investigated to check the effect of the polypyrrole layer on the electrochemical performance.the Brain Korea 21 program of the Korea Ministry of Education and Korea Science and Engineering Foundation through the Hyperstructured Organic Materials Research Center

A Simple Synthesis of Mesoporous Carbons with Tunable Mesopores Using a Colloidal Template-Mediated Vapor Deposition Polymerization

Mesoporous carbons with highly uniform and tunable mesopores were fabricated by one-step vapor deposition polymerization (VDP) using colloidal silica particles as templates and polyacrylonitrile (PAN) as a carbon precursor.This work was supported by the Brain Korea 21 program of the Korea Ministry of Education and Korea Science and Engineering Foundation through the Hyperstructured Organic Materials Research Center

Heavy metal ion adsorption onto polypyrrole-impregnated porous carbon

Polypyrrole-impregnated porous carbon was readily synthesized using vapor infiltration polymerization of pyrrole monomers. The results show that the functionalized polymer layer was successfully coated onto the pore surface of carbon without collapse of mesoporous structure. The modified porous carbon exhibited an improved complexation affinity for heavy metal ions such as mercury, lead, and silver ions due to the amine group of polypyrrole. The introduced polypyrrole layer could provide the surface modification to be applied for heavy metal ion adsorbents. Especially, polymer-impregnated porous carbon has an enhanced heavy metal ion uptake, which is 20 times higher than that of adsorbents with amine functional groups. Furthermore, the relationship between the coated polymer amount and surface area was also investigated in regard to adsorption capacity.This work was supported by the Center for Advanced Materials Processing under the 21C Frontier Programs of the Ministry of Commerce, Industry and Energy (MOCIE)

Versatile Strategies for Fabricating Polymer Nanomaterials with Controlled Size and Morphology

The development of reliable synthetic routes to polymer nanomaterials with well-defined size and morphology is a critical research topic in contemporary materials science. The ability to generate nanometer-sized polymer materials can offer unprecedented, interesting insights into the physical and chemical properties of the corresponding materials. In addition, control over shape and geometry of polymer nanoparticles affords versatile polymer nanostructures, encompassing nanospheres, core-shell nanoparticles, hollow nanoparticles, nanorods/ fibers, nanotubes, and nanoporous materials. This review summarizes a diverse range of synthetic methods (broadly, hard template synthesis, soft template synthesis, and template-free synthesis) for fabricating polymer nanomaterials. The basic concepts and significant issues with respect to the synthetic strategies and tools are briefly introduced, and the examples of some of the outstanding research are highlighted. Our aim is to present a comprehensive review of research activities that concentrate on fabrication of various kinds of polymer nanoparticles.the Center for Advanced Materials Processing under the 21C Frontier R&D Programs of the Ministry of Commerce, Industry and Energy (MOCIE), the Fundamental R&D Program for Core Technology of Materials of the MOCIE, and the SystemIC2010 Project of the MOCIE

Fabrication and characterization of polyaniline coated carbon nanofiber for supercapacitor

Polyaniline coated carbon nanofiber was fabricated using one-step vapor deposition polymerization technique. Fourier transform infrared (FT-IR) spectra and transmission electron microscope (TEM) images indicated that uniform and ultrathin conducting polymer layers were formed on the carbon nanofiber surfaces regardless of the coating thickness. It was also confirmed that the thickness of polyaniline layer could be conveniently tuned by the feeding amount of monomer. The coating thickness was dependent on initiator/monomer ratio, the vacuum pressure of reaction chamber and polymerization temperature. Among them, the vacuum pressure was a major factor to control the coating thickness of polyaniline onto the carbon nanofiber surface. In addition, the electrochemical analysis demonstrated that polyaniline coated carbon nanofiber showed an improved performance as supercapacitor. The specific capacitance of polyaniline coated carbon nanofiber exhibited a maximum value of 264 F/g when the thickness of polyaniline layer was ca. 20 nm.This work was supported by the Brain-Korea 21 Program of the Korea Ministry of Education and Korea Science and Engineering Foundation through Hyperstructured Organic Materials Research Center in Seoul National University

Proper fraction of inspired oxygen for reduction of oxygen-induced canine cerebrospinal fluid hyperintensity on fluid attenuation inversion recovery sequence using low-field magnetic resonance imaging

Oxygen-induced cerebrospinal fluid (CSF) hyperintensity artifact is inevitable in fluid attenuation inversion recovery (FLAIR) magnetic resonance (MR) images of anesthetized animals. This experimental study aimed to confirm the occurrence of this artifact on low-field magnetic resonance imaging (MRI), and to determine the fraction of inspired oxygen (FiO(2)) that is safe and does not induce this artifact in canine brain MRI. Six healthy dogs underwent brain FLAIR MR scans under general anesthesia with 21%, 30%, 50%, 70%, and 100% FiO(2). The signal intensity (SI) ratio was calculated as the SI of CSF spaces divided by that of normalizing regions. The SI ratios of 21% FiO(2) images were significantly different from those of 100% FiO(2) images, indicating the presence of artifacts on 100% FiO(2) images. The SI ratios of 30% FiO(2) images were not significantly different from those of 21% FiO(2) images for any of CSF spaces. However, they were significantly different from those of 100% FiO(2) images in the cerebral sulci, third ventricle, interpeduncular cistern, mesencephalic aqueduct, and subarachnoid space at the level of the first cervical vertebra (P<0.05). All dogs had normal partial pressure of arterial oxygen (PaO2) during inhalation of 30% FiO(2), while two dogs had low PaO2 during inhalation of 21% FiO(2). Our findings support the hypothesis that high FiO(2) induces CSF hyperintensity artifact on low-field FLAIR MR images in dogs. FiO(2) of 30% is appropriate for obtaining brain FLAIR MR images with fewer artifacts in dogs.Y

Macroporous Organic Thin Film Using Small-Molecule Heterointerface for High-Performance Organic-Transistor-Based Chemical Sensors

The semiconductor–dielectric interface significantly affects the performance and the reliability of field-effect transistors. Controlling this interface is an important issue to improve device performance in the organic electronics community. Here we report an approach that utilizes an organic heterointerface to improve the crystallinity and control the morphology of an organic thin film. Pentacene is used as an active layer above, and m-bis(triphenylsilyl)benzene (TSB3) is used as the bottom layer. Sequential evaporations of these materials result in high-quality organic thin films with indistinct grain boundaries and nanometre-sized pores. The pentacene film exhibits high mobility, and the pore-rich structure improves the sensitivity of organic-transistor-based chemical sensors

High-Performance FET-Type Chemical Sensors Based on Organic Semiconductor Thin Films with Macroporous Structures

The physical structure of an organic solid is strongly affected by the surface of the underlying substrate. Controlling this interface is an important issue to improve device performance in the organic electronics community. Here we report an approach that utilizes an organic heterointerface to improve the crystallinity and control the morphology of an organic thin film. Pentacene is used as an active layer above, and m-bis(triphenylsilyl)benzene is used as the bottom layer. Sequential evaporations of these materials result in extraordinary morphology with far fewer grain boundaries and myriad nanometre-sized pores. The pore-rich structure improves the sensitivity of organic-transistor-based chemical sensors