Woo Taik Lim

Effect of pH on Fenton and Fenton‐like oxidation

The lifetime of H2O2 is an important factor in the feasibility of Fenton’s reaction for soil and groundwater remediation. The lifetime of H2O2 was evaluated in Fenton’s reaction and Fenton‐like reactions with haematite and magnetite. H2O2 was more stable in the Fenton‐like reaction than in the Fenton’s reaction. The lifetime of H2O2 was also highly affected by the solution pH, and a pH buffered acidic condition was preferred. Fenton’s reaction and Fenton‐like reaction were tested for phenanthrene adsorbed on sand. Fenton‐like reaction and acidic condition showed better degradation rates in comparing with those of Fenton’s reaction and unbuffered systems. The dissolved iron species were measured in the Fenton’s reaction, and Fenton‐like reaction with haematite as a function of pH. In the presence of H2O2, ferric iron was the major dissolved iron species and the pH buffered to acidic condition maintained relatively high levels of dissolved iron in the aqueous solution. The higher iron concentration in the solution contributed to effective production of hydroxyl radical and degradation of organic contaminants.

Functionalised azetidines as ligands: Species derived by selective alkylation at substituent-nitrogen

Selective functionalisation of the tridentate ligand 1-(2-aminoethyl)-3-methyl-3-(2-pyridyl)azetidine at its terminal amino-nitrogen atom can be readily achieved by both reductive alkylation and simple alkylation reactions to give tri-, quadri-, quinque- and sexi-dentate derivatives. Simple alkylation by 2-picolinyl chloride provides the only example of a second reaction pathway where the azetidine ring of the reactant has undergone activation towards ring opening. Structural characterisation of the Cu(II) complexes of these ligands has revealed several remarkable aspects of their solid-state coordination chemistry, including the formation of infinite helical aggregates through pi-stacking and tetramerisation through carboxylate bridging, as well as further examples of the crystallisation of mixed species found to be rather common with complexes of the parent ligand.

Chromaticity (b*) and Transmittance of ITO Thin Films Deposited on PET Substrate by Using Roll-to-Roll Sputter System

Indium Tin Oxide (ITO) thin films on Polyethylene Terephtalate (PET) substrate were prepared by Roll-to-Roll sputter system with targets of 5 wt% and 10 wt% SnO2 at room temperature. The influence of the chromaticity (b*) and transmittance properties of the ITO Films were investigated. The ITO thin films were deposited as a function of the DC power, rolling speed, and Ar/O2 gas flow ratio, and then characterized by spectrophotometer. Their crystallinity and surface resistance were also analyzed by X-ray diffractometer and 4-point probe. As a result, the chromaticity (b*) and transmittance of the ITO films were broadly dependent on the thickness, which was controlled by the rolling speed. When the ITO films were prepared with the DC power of 300 W and the Ar/O2 gas flow ratio of 30/1 sccm using 10 wt% SnO2 target as a function of the rolling speeds 0.01 through 0.10 m/min, its chromaticity (b*) and transmittance were about -4.01 to 11.28 and 75.76 to 86.60%, respectively. In addition, when the ITO films were deposited with the DC power of 400W and the Ar/O2 gas flow ratio of 30/2 sccm used in 5 wt% SnO2 target, its chromaticity (b*) and transmittance were about -2.98 to 14.22 and 74.29 to 88.52%, respectively.

Computational Design of Functional Amyloid Materials with Cesium Binding, Deposition and Capture Properties

Amyloid materials are gaining increasing attention as promising materials for applications in numerous fields. Computational methods have been successfully implemented to investigate the structures of short amyloid-forming peptides, yet their application in the design of functional amyloid materials is still elusive. Here, we developed a computational protocol for the design of functional amyloid materials capable of binding to an ion of interest. We applied the protocol in a test case involving the design of amyloid materials with cesium ion deposition and capture properties. As part of the protocol, we used an optimization-based design model to introduce mutations at non-β-sheet residue positions of an amyloid designable scaffold. The designed amino acids introduced to the scaffold mimic how amino acids bind to cesium ions according to experimentally resolved structures and also aim at energetically stabilizing the bound conformation of the pockets. The optimum designs were computationally validated using a series of simulations and structural analysis to select the top designed peptides, which are predicted to form fibrils with cesium ion binding properties for experimental testing. Experiments verified the amyloid-forming properties of the selected top designed peptides, as well as the cesium ion deposition and capture properties by the amyloid materials formed. This study demonstrates the first, to the best of our knowledge, computational design protocol to functionalize amyloid materials for ion binding properties and suggests that its further advancement can lead to novel, highly promising functional amyloid materials of the future.