San Hua Lim

Sensitization to local dust-mite fauna in Singapore.

Background: Recent studies showed the presence of a unique dust‐mite fauna in the indoor environment of Singapore. Immediate hypersensitivity to these dust mites, along with other known indoor allergens, may play a role in the pathogenesis of allergic respiratory diseases. This study evaluated the sensitization rates of the local atopic population to these allergens.

Evaluation of the allergenicity of tropical pollen and airborne spores in Singapore

Background: Sensitization to pollen and spores of the Southeast Asian tropical region is not well documented. This study evaluated the allergenicity of the tropical airspora in Singapore.

FUNCTIONALIZATION EFFECT ON THE ELECTRONIC PROPERTIES OF SINGLE WALLED CARBON NANOTUBES

OH-functionalized single-walled carbon nanotubes (SWNTs), i.e. SWNT–OH, were prepared through the ball-milling of purified SWNTs with KOH. The composition of the pristine SWNTs bulk sample was characterized by resonance Raman scattering. The OH-functionalization-induced shrinking of the energy gap, the charge transfer from C to –OH, the depletion of top valence band density, the modification of energy band structure and the significant reduction in the work function of SWNTs were experimentally studied by variable temperature FTIR, Raman scattering, ultra-violet photoelectron spectroscopy, X-ray photoelectron energy loss spectroscopy etc. Ab initio calculation was also performed to assist the discussion.

Plasma-Assisted Synthesis of Carbon Nanotubes

The application of plasma-enhanced chemical vapour deposition (PECVD) in the production and modification of carbon nanotubes (CNTs) will be reviewed. The challenges of PECVD methods to grow CNTs include low temperature synthesis, ion bombardment effects and directional growth of CNT within the plasma sheath. New strategies have been developed for low temperature synthesis of single-walled CNTs based the understanding of plasma chemistry and modelling. The modification of CNT surface properties and synthesis of CNT hybrid materials are possible with the utilization of plasma.

Binary metal sulfides and polypyrrole on vertically aligned carbon nanotube arrays/carbon fiber paper as high-performance electrodes

Pseudocapacitive materials, such as binary metal sulfides, show great promise as electrode candidates for energy storage devices due to their higher specific capacitance than that of mono-metal sulfides and binary metal oxides, but generally suffer from low energy densities when assembled in supercapacitor devices. To push the energy density limit of pseudocapacitive materials in devices, a new class of electrode materials with favorable architectures is strongly needed. Here, rationally designed and coaxially grown Ni–Co–S and polypyrrole on vertically aligned carbon nanotube (VA-CNT) arrays/3D carbon fiber paper (CFP) is presented as a novel freestanding electrode for energy storage devices. Our study has revealed that the catalyst preparation is the key step and the presence of an Al2O3 buffer layer is essential for the growth of VA-CNTs. The 3D hierarchical VA-CNTs/CFP allows high areal loading and high utilization efficiency of the active materials. The binder-free asymmetric energy storage devices with Ni–Co–S/VA-CNTs/CFP as the positive electrode and polypyrrole/VA-CNTs/CFP as the negative electrode, respectively, demonstrate a high energy density of 82 W h kg−1 at 200 W kg−1.

A molecular quantum wire of linear carbon chains encapsulated within single-walled carbon nanotube (Cn@SWNT)

Pure sp-hybridized linear carbon chains possess unique physical properties of one-dimensional (1D) system. However, linear carbon chains are highly unstable and require to be stabilized within a matrix for direct experimental studies. Here we report a plasma-enhanced chemical vapor deposition method to encapsulate and stabilize linear carbon chains (Cn) within vertically aligned SWNTs to form a sp-sp2 hybrid system (Cn@SWNT). Intense Raman signals at ∼1760–1860 cm−1 (L bands) indicate the presence of linear carbon chains within SWNTs. Electron transport of Cn@SWNT bundle exhibits Luttinger-liquid behavior.