Publications by authors named "Kap Seung Yang"

Niobium pentoxide (NbO)-based materials have attracted significant interest for application in diverse fields. Unfortunately, the employment of these materials as electrodes of lithium-ion batteries (LIBs) is limited by several inherent drawbacks. The present study demonstrated the synthesis of composites comprising homogeneous graphene-wrapped niobium pentoxide (GNbO) encapsulated in carbon nanofibers (CNFs) for utilization as binder- and additive-free anodes in LIBs.

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The roles of the Fc receptor (FcR) in protection or inflammatory disease after respiratory syncytial virus (RSV) vaccination and infection remain unknown. Virus-like particles containing RSV fusion proteins (RSV F-VLPs) induce T-helper type 1 antibody responses and protection against RSV. Heterologous RSV F-VLP prime and formalin-inactivated RSV (FI-RSV) boost vaccination has been reported to be effective in providing protection without inflammatory disease.

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Nitrogen enriched carbon nanofibers have been obtained by one-step carbonization/activation of PAN-based nanofibers with various concentrations of melamine at 800 °C under a N atmosphere. As synthesised carbon nanofibers were directly used as electrodes for symmetric supercapacitors. The obtained PAN-MEL fibers with 5% melamine stabilised at 280 °C and carbonized at 800 °C under a nitrogen atmosphere showed excellent electrochemical performance with a specific capacitance of up to 166 F g at a current density of 1A g using 6 M KOH electrolyte and a capacity retention of 109.

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In this study, isotropic pitch-based carbon fibers were prepared from a mixture of petroleum residue and graphene nanoplatelets with different contents. The softening point and synthetic yield of synthesized isotropic pitches were analyzed and compared to characterize the nature of the pitches. The surface and thermal characteristics of the fibers were observed using scanning electron microscopy and thermogravimetric analysis (TGA), respectively.

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It is important to fabricate nanostructured architectures comprised of functional components for a wide variety of applications because precise structural control in the nanometer regime can yield unprecedented, fascinating properties. Owing to their well-defined microstructural characteristics, it has been popular to use carbon nanospecies, such as nanotubes and graphene, in fabricating nanocomposites and nanohybrids. Nevertheless, it still remains hard to control and manipulate nanospecies for specific applications, thus preventing their commercialization.

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Nanostructured poly(m-aminophenol) (PmAP) coated freestanding carbon nanofiber (CNF) mats were fabricated through simple in situ rapid-mixing polymerization of m-aminophenol in the presence of a CNF mat for flexible solid-state supercapacitors. The surface compositions, morphology and pore structure of the hybrid mats were characterized by using various techniques, e.g.

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Novel pyrrolyl hydrazones and their copper complexes have been synthesized and characterized using analytical and spectral techniques to show the tetrahedral geometry for Cu(II) complexes. Biological activities of hydrazones have been assessed to understand the role of metal ion on their biological activity and the effect of pyrrolyl hydrazones. In vitro antitubercular activity against Mycobacterium tuberculosis of the metal complexes (13b and 13r) exhibited the highest antitubercular activity that are quite close to rifampicin (0.

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A high-performance Si/carbon/graphite composite in which Si nanoparticles are attached onto the surface of natural graphite by carbonization of coal-tar pitch is proposed for use in lithium-ion batteries. This multicomponent structure is favorable for improving Li(+) storage capability because the amorphous carbon layer encapsulating Si nanoparticles offers sufficient electric conductivity and strong elasticity to facilitate relaxation of strain caused by electrochemical reaction of Si during cycles. The Si/carbon/graphite composite exhibits a specific capacity of 712 mAh g(-1) at a constant current density of 130 mA g(-1), and maintains more than 80% of its initial capacity after 100 cycles.

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We report here the synthesis, antibacterial and antitubercular evaluation of 61 novel pyrrolyl derivatives bearing pyrazoline, isoxazole and phenyl thiourea moieties. Molecular docking was carried out on enoyl ACP reductase from Mycobacterium tuberculsosis using Surflex-Dock, which is one of the key enzymes involved in type II fatty acid biosynthetic pathway of Mycobacterium tuberculosis, an attractive target for designing novel antitubercular agents. Docking analysis of the crystal structure of ENR performed using Surflex-Dock in Sybyl-X 2.

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A new synthetic method is demonstrated for transforming rice husks into bulk amounts of graphene through its calcination and chemical activation. The bulk sample consists of crystalline nano-sized graphene and corrugated individual graphene sheets; the material generally contains one, two, or a few layers, and corrugated graphene domains are typically observed in monolayers containing topological defects within the hexagonal lattice and edges. Both types of graphenes exhibit atomically smooth surfaces and edges.

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The boric oxide deposition was performed to improve the oxidation resistivity of carbon nanofiber (CNF) from electrospinning at elevated temperatures. The stabilized electrospun polyacrylonitrile (PAN) nanofibers were coated with boric oxide, followed by heat treatment up to 1000, 1200, and 1400 degrees C in an inert nitrogen atmosphere. The relative oxidation resistance of boric oxide-coated CNFs showed oxidation resistive property, which was determined by weight loss after running a thermogravimetric analyzer (TGA) under air flow.

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Combinative one-pot Si-Si/Si-O dehydrocoupling of hydrosilanes with alcohols (1:1.5 mole ratio), mediated by a mixture of AgNO3-AuCl3 (100/1 mole ratio) rapidly produced poly(alkoxysilane)s in reasonably high yield. The addition of small amount of gold complex to the reaction mixture effectively accelerated the coupling reaction compared to the reaction rate with AgNO3 alone.

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The generation of silver nanoparticle/bis(o-phenolpropyl)silicone composites have been facilitated by the addition of sodium tetrachloroaurate or gold(Ill) chloride (< 1 wt% of NaAuCl4 or AuCl3) to the reaction of silver nitrate (AgNO3) with bis(o-phenolpropyl)silicone [BPPS, (o-phenolpropyl)2(SiMe2O)n, n = 2,3,8,236]. TEM and FE-SEM data showed that the silver nanoparticles having the size of < 20 nm are well dispersed throughout the BPPS silicone matrix in the composites. XRD patterns are consistent with those for polycrystalline silver.

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Codehydrocoupling (in the presence of various inorganic B, Al-hydrides) followed by borane-capping (with Ph2BCl) of 1,1-dihydrotetraphenylsilole (1) and 1,1-dihydrotetraphenylgermole (2) (9:1 mole ratio) gave electroluminescent poly(silole-co-germole)s containing borane-ends (3) in high yield. The polymerization yield and molecular weight with Selectrides increase in the order L-Selectride < N-Selectride < K-Selectride. The molecular weights with B, Al-inorganic hydrides increase in the order L-Selectride < Red-Al View Article and Find Full Text PDF

The one-pot synthesis and characterization of silver nanoparticle-poly(p-Br-phenylsilane) composites have been carried out. The conversion of silver(+1) salt to stable silver(0) nanoparticles is promoted by poly(p-Br-phenylsilane), Br-PPS possessing both possible reactive Si-H bonds in the polymer backbone and C-Br bonds in the substituents. The composites were characterized using XRD, TEM, FE-SEM, and solid-state UV-vis analytical techniques.

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The formation of silver nanoparticle/bis(o-phenolpropyl)silicone composites have been promoted by the addition of chloroplatinic acid (<2 wt%) to the reaction of silver nitrate with bis(o-phenolpropyl)silicone BPPS [(o-phenolpropyl)2(SiMe2O)n, = 2, 3, 8, 236]. TEM and FE-SEM data exhibit that the silver nanoparticles having the size of <20 nm are well dispersed throughout the BPPS matrix in the composites. XRD patterns are consistent with those for polycrystalline silver.

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A simple one-step method was used for preparing the beta-cyclodextrin/polyacrylonitrile (PAN) nanofibers deposited with silver nanoparticles by electrospinning and followed by the reduction of the Ag+ ions. The nano-composite fibers were stabilized at 280 degrees C in air and activated at 800 degrees C for 1 h in steam/N2. The structures of nano-composite fibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), fourier-transform infrared (FTIR) spectroscopy, and X-ray diffraction analysis (XRD).

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To improve the anti-oxidation properties of carbon fibers (CFs), the sol-gel method followed by pyrolysis was used to coat CFs with SiC/SiO2 ceramic coatings. The SiO2 sol-gel coating was performed by dip coating a PAN(polyacrylonitrile)-based stabilized fiber (PSF) in a silica sol prepared by the polycondensation of tetraethylorthosilicate (TEOS) in the presence of an acidic catalyst. The PSF coated with SiO2 sol then underwent heat treatments at high temperatures in an inert atmosphere to deposit the SiC/SiO2 and carbonize the deposited fibers.

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Codehydrocoupling (with various inorganic hydrides) followed by stannane-capping (with Ph2SnHCI) of 1,1-dihydrotetraphenylsilole (1) and 1,1-dihydrotetraphenylgermole (2) (9:1 mol ratio) produces electroluminescent stannane-terminated poly(silole-co-germole)s (3) in high yield. The polymerization yield and molecular weight with Selectride increase in the order L-Selectride < N-Selectride < K-Selectride. The molecular weights increase in the order L-Selectride < Red-Al < N-Selectride < K-Selectride < Super-Hydride.

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Si-Si/Si-O dehydrocoupling of hydrosilanes with alcohols (1:1.5 mole ratio), catalyzed by AgNO3 which converted to Ag(0) colloidal nanoparticles, gave poly(alkoxysilane)s in one-pot in moderate to high yield. The hydrosilanes include p-X-C6H4SiH3 (X = H, CH3, OCH3, F), PhCH2SiH3, and (PhSiH2)2.

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Silver nanoparticle/bis(o-phenolpropyl)silicone composites have been synthesized by the reduction of silver nitrate with bis(o-phenolpropyl)silicone BPPS [(o-phenolpropyl)2(SiMe2O)n, n = 2, 3, 8, 236]. TEM and FE-SEM data clearly show that the silver nanoparticles with the size of < 20 nm are well dispersed throughout the BPPS matrix in the composites. XRD patterns are consistent with those for multicrystalline silver.

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The electron beam (EB) irradiation effects of TiO2 deposited on carbon nanofibers (CNFs) were studied aiming the improvement of the photocatalytic activity. The EB irradiation contributed to an increase in crystallinity of the anatase resulting an improvement of the photocatalytic activity through the oxidation (ionization) of the doped TiO2 and leading to uniform distribution TiO2 particles on the CNFs surface. The photoactivity of the catalyst was measured by the decoloration of the methylene blue (MB) with time under UV irradiation.

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A simple but controllable way of altering the surface nature of carbon fibers, without sacrificing their intrinsic mechanical properties, is demonstrated using electron beam irradiation. Such treatment leads to physically improved roughness as well as chemically introduced hydrophilic oxygen-containing functional groups on the surface of carbon fibers that are essential for assuring an efficient stress transfer from carbon fibers to a polymer matrix.

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Si-Si/Si-O dehydrocoupling of hydrosilanes with alcohols (1:1.5 mole ratio), catalyzed by group VIII metallocenes Cp2M' (M' = Co, Ni) which converted to Co(O)/nickel(O) colloidal nanoparticles, produced poly(alkoxysilane)s in one-pot in high yield. The hydrosilanes include p-X-C6H4SiH3 (X = H, CH3, OCH3, F), PhCH2SiH3, and (PhSiH2)2.

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Silver-polyphenylsilane nanocomposites have been effectively prepared by the dehydrocoupling reaction of phenylsilane (PS, PhSiH3) to polyphenylsilane (PPS, [PhSiH]n) in the presence of silver nitrate. The one-step reduction of Ag(+1) nitrate to stable Ag(0) nanoparticles is mediated by PS, resulting in the formation of Ag-PPS composites. The Ag-PPS nanocomposites were characterized by various analytical techniques such as XRD, TEM, FE-SEM, and solid-state UV-vis.

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