Using electrophoretic deposition to identify protein charge in biological medium

Protein adsorption is the first step involved in establishing a suitable integration between a biomaterial and host tissue. It is therefore of highest interest to know the electric charge of proteins present in the relevant medium to be able to predict the behaviour of cells on given surfaces. In this study, electrophoretic deposition (EPD) was used as a simple method to identify the charge of proteins present in biological medium. In the model experiment carried out here, EPD was conducted using a biological medium containing 10% fetal calf serum (FCS) and the charge of the protein was determined by examining the migration of the protein in the EPD cell under a certain applied voltage. In addition, the suitability of EPD of proteins to deliver tailored surfaces for enhanced bioactivity or for controlled deposition of protein films on metallic surfaces was explored.     

Performance of vanadium-oxygen redox fuel cell

A promising approach to improving the energy density of the all-vanadium redox flow battery while also saving on raw materials costs, is to eliminate the positive half-cell electrolyte and replace it with an air electrode to produce a hybrid vanadium–oxygen redox fuel cell (VOFC). This concept was initially proposed by Kaneko et al. in 1992 and first evaluated at the University of New South Wales by Menictas and Skyllas-Kazacos in 1997. In this project the performance of the VOFC over a range of temperatures and using different types of membranes and air electrode assemblies was evaluated. Despite early problems with the membrane electrode assemblies that saw separation of the membrane due to swelling and expansion during hydration, with improved fabrication techniques, this problem was minimized and it was possible to operate a 5-cell VOFC system for a total of over 100 h without any deterioration in its performance.     

Electrochemical synthesis of magnesium borate whisker

This study successfully synthesised magnesium borate (Mg₂B₂O₅) whiskers using a simpler electrochemical method and lower energy consumption compared with traditional methods. Metallic magnesium was anodised under low-voltage conditions in a borate solution containing ethanol/water mixtures and poisoning agents. The composition and morphology of the magnesium borate whiskers were determined by X-ray diffraction and scanning electron microscope measurements, respectively. The magnesium borate whiskers were 6–8 μm long, each with a diameter of 500 nm. The ratio of the length to the diameter ranges from 12:1 to 16:1. The average current efficiency was 72.6%.     

V–I characteristics of solid polymer electrolytic (SPE) dehumidifier

Measurements of the V–I characteristics of a solid polymer electrolytic (SPE) dehumidifier were done using a modified SPE dehumidifier with four electrodes which included two electrodes to carry the main current and the other two electrodes to measure the voltages applied to the electrical double layer, which are the boundary voltages between the electrodes and the SPE membrane. The measured results were analyzed using the Butler-Volmer equation to examine the validity of the measurements. The current flowing in the dehumidifier is produced by the decomposition of water near the anode. Therefore, under a steady-state condition, the current should be proportional to the supply rate of water to the anode. On the other hand, a two-layer model for the SPE dehumidifier presented in our previous article showed that the current flowing in the dehumidifier was roughly proportional to the water content in the vicinity of the anode. These results were introduced for interpretation of the V–I measurements of the SPE dehumidifier. It was concluded that the dehumidifier current was expressed in the form of a Butler-Volmer equation as a function of the electrode boundary voltages which were the voltages across the boundary between the electrodes and the SPE membrane. An experimental formula for the current under a steady-state condition was developed as a function of the water content near the anode and the boundary voltages.     

Synthesis,characterization and evaluation of phosphorylated resins in the removal of Pb<Superscript>2+</Superscript> from aqueous solutions

Phosphinic-derivative poly(styrene-co-divinylbenzene)-based on PS–DVB copolymers with different porosity degrees have been prepared by aromatic electrophilic substitution reaction using PCl₃/AlCl₃ followed by base-promoted hydrolysis. The phosphorylation reaction was analyzed by infra-red spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetry (TG/DTG). In addition, the phosphorous content of the phosphorylated copolymers was determined by spectrophotometry using the method based on sodium molybdate reactant so that the extension of that modification could be assessed. The performance of the phosphorylated resins in the extraction of Pb²⁺ from aqueous solutions in a batch system was also evaluated. The Pb²⁺ content was determined by atomic absorption spectrometry (AAS). These materials presented excellent extraction capacity under the contact time of 30 min and pH 6.     

A study on dynamic rheological characterisation of electron beam crosslinked high vinyl styrene butadiene styrene block copolymer

Crosslinking of elastomers using electron beam radiation has several advantages over conventional method. It is accomplished much faster, in a more environmental friendly approach and in a much simpler manner. When fast moving electrons that are generated from electron accelerators are targeted on a polymer matrix, they primarily crosslink the polymer. However, in the process, some chain scission may also occur. In this work, a high vinyl (~50%) styrene–butadiene–styrene (S–B–S) block copolymer was used as the base polymer. Radiation doses were varied from 25 to 300 kGy. A detailed investigation was made to understand the effect of electron beam radiation on the rheological properties such as storage modulus, loss modulus, storage viscosity and complex viscosity of the block copolymer under strain and frequency sweeps performed in a Rubber Process Analyzer (RPA). Recyclability of the crosslinked S–B–S polymer was also explored by RPA and mechanical studies.     

Molecular motion and detrapping behavior of trapped space charges in polyvinyl pyrrolidone: a thermally stimulated depolarization current study

The discharging process of polyvinyl pyrrolidone electret under two different heating rates 3.5 and 2 °C/min has been investigated by the measurement of thermally stimulated depolarization current (TSDC) in the temperature range from 30 to 250 °C. The TSDC spectra of PVP shows three peaks located at 70 ± 10, 150 ± 10, and 230 ± 10 °C, respectively. When explaining the TSDC spectra, this thesis deduced that the first peak, β peak, originates from side group relaxation; the second peak, α peak, corresponds to the relaxation of the frozen dipoles on the molecule chain segments during glass transition; the third peak, ρ peak, is attributed to the detrapping of the trapped space charge under thermal stimulation. The current of the ρ peak is remarkably strong due to the fact that PVP molecules’ side groups—the pyrrolidone rings containing lactam structure—are strong polar groups which cause the great increase in the number of bulk traps, trapped space charge, as well as detrapped space charge under thermal stimulation.     

Interfacial adhesion study on UHMWPE fiber-reinforced composites

Ultrahigh molecular weight polyethylene (UHMWPE) fiber has many outstanding properties. However, poor interfacial adhesion of the UHMWPE fiber/polymer matrix interface limits its applications as reinforcement in high performance polymer matrix composites. Therefore, a new thermosetting resin system, named PCH, which is only composed of carbon and hydrogen elements, has been developed according to law of similar mutual solubility and the structural characteristics of UHMWPE fiber. The adhesion property was investigated by mechanical properties test, thermal performance test, and polymer solution properties test. Test results show that a strong interaction occurs between UHMWPE fiber and the PCH matrix due to the structural and polar similarity. In the case of slight difference between solubility parameters of UHMWPE fiber and cured PCH resin, it is found that the wettability of PCH resin on surface of the fiber can be improved and the difference between the coefficients of thermal expansion of the matrix and the fiber decreases with the increase of styrene added into the PCH. An optimal interfacial adhesion can be obtained as the ratio of PCH/styrene is approximately 55/45.     

Preparation and controlled release of degradable polymeric ketoprofen–saccharide conjugates

A facile and efficient enzymatic and polymerization process was used to prepare polymeric prodrugs of ketoprofen with saccharide side chains. The chains included branches that included glucose, mannose, galactose, and lactose, and these were synthesized through free radical reaction. The prodrugs were characterized by FT-IR, NMR, and GPC and drug-loading capacity was influenced by varying the ratios of initiator and monomers (range 32.13 and 68.56% w/w). In vitro release characteristics of the polymeric drugs were systematically evaluated over the pH range 1.2–8.0 and the release profiles indicated that the hydrolytic nature of polymers were strongly depended on the variation in saccharide content, carbon chain length, and pH. The outcomes from this study demonstrate the importance of carbohydrate structures and how these are linked to drug release.     

Protective effect of nicotinic acid on human albumin during UV-C irradiation

The potential of nicotinic acid (NiAc), a vitamin B3 compound with antioxidant activity, to protect human albumin against the damage caused by exposure to 254-nm UV-C radiation was investigated. Experiments performed at irradiance levels of 3.5–15 W m⁻² and application times between 5 and 30 min showed that albumin undergoes rapid dose-dependent aggregation when subjected to irradiation. Addition of 0.2 mM NiAc to the albumin solution resulted in a remarkable reduction of protein damage. Protection provided by NiAc was effective up to radiation doses of about 30 kJ m⁻², which are significantly higher than those required for complete microbial and viral inactivation.