The preparation of HEMA-MPC films for ocular drug delivery

There is a need to prolong drug residence time using a biocompatible formulation in the subconjunctival space after surgery to treat glaucoma. Drug releasing discs were prepared with 2-(hydroxyethyl)methacrylate (HEMA) and 2-methacryloyl-oxyethyl phosphorylcholine (MPC). The ratio of bound water (Wb) to free water (Wf) ratio increased from 1:0.3 to 1:6.8 with increasing MPC (0 to 50%, w/w). The optimal balance between water content, SR and mechanical strength were obtained with 10% MPC (w/w) hydrogels. Water-alcohol mixtures were examined to facilitate loading of poorly soluble drugs, and they showed greater hydrogel swelling than either water or alcohol alone. The SR was 1.2 ± 0.02 and 3.3 ± 0.1 for water and water:ethanol (1:1) respectively. HEMA-MPC (10%) discs were loaded with dexamethasone using either water:ethanol (1:1) or methanol alone. Drug release was examined in an outflow rig model that mimics the subconjunctival space in the eye. Dexamethasone loading increased from 0.3 to 1.9 mg/disc when the solvent was changed from water:ethanol (1:1) to methanol with the dexamethasone half-life (t½) increasing from 1.9 to 9.7 days respectively. These encouraging results indicate that HEMA-MPC hydrogels have the potential to sustain the residence time of a drug in the subconjunctival space of the eye

Coconut oil based hybrid fuels as alternative fuel for deisel engines

Problem Statement: The use of vegetable oils as a fuel in diesel engines causes some problems due to their high viscosity compared with diesel. Various techniques and methods are used to solve the problems resulting from high viscosity. Approach: One of the techniques is the preparation of a microemulsion fuel, called a hybrid fuel. In this study, hybrid fuels consisting of coconut oil, ethanol and octan-1-ol were prepared with an aim to test their suitability as a fuel for diesel engines. Density, viscosity and gross calorific values of these fuels were determined and the fuels were used to run a direct injection diesel engine. The engine performance and exhaust emissions were investigated and compared with that of diesel and coconut oil. Results: The experimental results show that the engine efficiency of the hybrid fuels is comparable to that of diesel. As the percentage of ethanol and/or octan-1-ol increased, the viscosity of the hybrid fuels decreased and the engine efficiency increased. The exhaust emissions were lower than those for diesel, except carbon monoxide, which increased. Conclusions/Recommendations: Hence, it is concluded that these hybrid fuels can be used successfully as an alternative fuel in diesel engines without any modifications. Their completely renewable nature ensures that they are environmentally friendly

Preparation, characterisation, engine performance and emission characteristics of coconut oil based hybrid fuels

In this study, hybrid fuels consisting of coconut oil, aqueous ethanol and a surfactant (butan-1-ol) were prepared and tested as a fuel in a direct injection diesel engine. After determining fuel properties such as the density, viscosity and gross calorific values of these fuels, they were used to run a diesel engine. The engine performance and exhaust emissions were investigated and compared with that of diesel. The experimental results show that the efficiency of the hybrid fuels is comparable to that of diesel. As the viscosity of the hybrid fuels decreased and approached that of diesel, the efficiency increased progressively towards that of diesel. The exhaust emissions were lower than those for diesel, except carbon monoxide emissions, which increased. Hence, it is concluded that these hybrid fuels can be used successfully as an alternative fuel in diesel engines without any modifications. Their completely renewable nature ensures that they are environmentally friendly with regard to their emissions characteristics

Eutectic solidification in phenanthrene-biphenyl system

179-183<span style="font-size:11.0pt;line-height:115%; font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:="" "times="" new="" roman";mso-fareast-theme-font:minor-fareast;mso-hansi-theme-font:="" minor-latin;mso-bidi-font-family:arial;mso-ansi-language:en-us;mso-fareast-language:="" en-us;mso-bidi-language:ar-sa"="">Solid-liquid equilibrium for binary mixtures of phenanthrene-biphenyl has been obtained by thaw-melt method The mechanism of eutectic solidification of this binary system has been investigated by spontaneous crystallization, linear velocity of crystallization and viscosity determination. Excess molar volume, excess viscosity, free-energy of activation for flow, and Grunberg Nissan parameter d have been calculated. The diffusion process has been found to be the dominant factor in explaining the decrease in the unidirectional velocity of crystallization as one component is added to the other and also explains the higher growth rate for the eutectic mixture.</span

Weed Hosts of Root-Knot Nematodes and Their Distribution in Fiji

Weeds can act as reservoir hosts of a range of pests and diseases. Information and knowledge on the host status of weeds to common pests and diseases can be used to develop integrated weed and pest management strategies. As part of a survey on the distribution and diversity of root-knot nematodes on crops in Fiji, the root-knot nematode host status of weeds was also studied. Weeds growing in root-knot nematode infested farms (n 5 189) and bioassay pot soil samples (n 5 277) were identified, and their host status was determined on the basis of a root gall and egg-mass index scale from 0 to 5. A total of 45 weed species were recorded as potential weed hosts of root-knot nematodes with a gall index from 1 to 5. Using the weed and tomato bioassay method, a total of 11 nonhost weed species were recorded with a gall index of 0, relative to infected tomato growing in pot soil samples. Common weeds infected by root-knot nematodes on farms and in bioassay pot soil included slender amaranth, old world diamond-flower, tropic ageratum, sicklepod, mimbra, balsamapple, purple bushbean, little ironweed, ivy gourd, and cutleaf groundcherry. The presence of egg masses on the weed hosts indicated their ability to sustain root-knot nematode populations and, thus, their potential to act as reservoir hosts. Nomenclature: Root-knot nematodes, Meloidogyne Go¨ldi; balsamapple, Momordica charantia L.; cutleaf groundcherry, Physalis angulata L.; ivy gourd, Coccinia grandis (L.) J. Voigt; little ironweed, Cyanthillium cinereum (L.) H. Rob.; old world diamond-flower, Oldenlandia corymbosa L.; purple bushbean, Macroptilium atropurpureum (Moc. & Sesse ex DC.) Urb.; seedbox, Ludwigia hyssopifolia (G. Don) Excell apud A. R. Fernandes; sicklepod, Senna obtusifolia (L.) H.S. Irwin & Barnaby; slender amaranth, Amaranthus viridus L.; tropic ageratum, Ageratum conyzoides L.; garden tomato, Solanum lycopersicum

Rheological Study of Genipin Cross-Linked Chitosan Hydrogels

This paper reports the rheological behavior of chitosan solutions that have been cross-linked with different amounts of genipin, at body temperature and physiological pH. The effect of the cross-linker loading on the rheological properties of hydrogels has been evaluated. The oscillatory time sweep method was used to monitor the dynamic viscoelastic parameters during in situ (i.e., in the rheometer) gelation experiments, enabling the determination of the gelation time. The stress and frequency sweeps were employed to measure G′ of the cured hydrogels. It was found that the solutions of chitosan cross-linked with genipin, under physiological conditions, could form relatively strong elastic gels when compared to those of pure chitosan. Moreover, the gelation time obtained from the crossover of G′′ and G′ was in excellent agreement with the value obtained from the Winter–Chambon criterion. A significant reduction on this parameter was achieved even at low genipin concentrations. This behavior suggests that these formulations are able to be produced in situ and thus constitute promising matrices for cells and bioactive molecule encapsulations