Responses of corals to chronic turbidity.

Dredging increases suspended sediment concentrations (SSCs), causing elevated water turbidity (cloudiness) and light attenuation. Close to dredging, low light periods can extend over many days, affecting phototrophic epibenthic organisms like corals. To improve the ability to predict and manage dredging impacts, we tested the response of corals to an extended period of elevated turbidity using an automated sediment dosing system that precisely controlled SSCs and adjusted light availability accordingly. Replicates of four common species of corals encompassing different morphologies were exposed to turbidity treatments of 0-100 mg L-1 SSC, corresponding to daily light integrals of 12.6 to 0 mol quanta m-2 d-1, over a period of ∼7 weeks. Symbiotic dinoflagellate density and algal pigment concentration, photosynthetic yields, lipid concentrations and ratios and growth varied among the turbidity treatments, with corals exhibiting photoacclimation within low turbidity treatments. A range of physiological responses were observed within the high turbidity treatments (low light), including bleaching and changes in lipid levels and ratios. Most corals, except P. damicornis, were capable of adjusting to a turbidity treatment involving a mean light level of 2.3 mol photons m-2 d-1 in conjunction with a SSC of 10 mg L-1 over the 7 week period.

Controlled release of 1-methylcyclopropene from its functionalised electrospun fibres under constant and linearly ramped humidity.

The methodology to electrospin polystyrene (PS) fibres functionalised with the inclusion complex between 1-methylcyclopropene (1-MCP) and α-cyclodextrin (α-CD) has been developed successfully. Due to limited availability, α-CD crystals instead of 1-MCP/α-CD complex were suspended in the electrospinning (ES) solutions to investigate the ES process. The ES solutions were characterised in terms of viscosity, conductivity and surface tension. Meanwhile, the fibres were subjected to scanning electron microscopy. The average fibre diameter was proportional to approximately one-sixth power of the capillary number of the ES solution. Viscosity, which was a function of PS concentration and α-CD loading, was the main property that dictated the spin ability of the ES solutions. ES fibres with 1.5-4.4 µm in diameter were produced with 12.5-20.0% (w/w) PS in ES solution and an equal amount of the inclusion complex for PS. In the case of the ES solutions of 20 wt% PS loaded with the inclusion complex from 0 to 100% (w/w) to PS, all the ES solutions were electrospinnable with the average diameter ranging from 3.8 to 4.6 µm. X-ray diffractometry indicated that the α-CD crystals were homogeneously suspended on the fibre mats. Confocal laser scanning microscopy showed that the crystals were suspended on the fibre mats while being coated with a layer of PS. The complex-functionalised fibre was formed from the ES solution of 20% PS and 50% (w/w) inclusion complex with the ES. The release characteristics of 1-methylcyclopropene (1-MCP) from the functionalised fibre and the inclusion complex were investigated real time under linearly ramping humidity conditions at constant temperatures with a home-built humidity regulating system coupled with gas chromatography. The irregular release profiles were successfully modelled and the activation energies of release for the functionalised fibre and inclusion complex were about 128 and 69 kJ/mol, respectively..

Effect of different dextrose equivalents of maltodextrin on oxidation stability in encapsulated fish oil by spray drying.

Encapsulating fish oil by spray drying with an adequate wall material was investigated to determine if stable powders containing emulsified fish-oil-droplets can be formed. In particular, the dextrose equivalent (DE) of maltodextrin (MD) affects the powder structure, surface-oil ratio, and oxidative stability of fish oil. The carrier solution was prepared using MD with different DEs (DE = 11, 19, and 25) and sodium caseinate as the wall material and the emulsifier, respectively. The percentage of microcapsules having a vacuole was 73, 39, and 38% for MD with DE = 11, 19, and 25, respectively. Peroxide values (PVs) were measured for the microcapsules incubated at 60 °C. The microcapsules prepared with MD of DE = 25 and 19 had lower PVs than those prepared with MD of DE = 11. The difference in PV can be ascribed to the difference in the surface-oil ratio of the spray-dried microcapsules.

Encapsulation of alcohol dehydrogenase in mannitol by spray drying.

The retention of the enzyme activity of alcohol dehydrogenase (ADH) has been studied in various drying processes such as spray drying. The aim of this study is to encapsulate ADH in mannitol, either with or without additive in order to limit the thermal denaturation of the enzyme during the drying process. The retention of ADH activity was investigated at different drying temperatures. When mannitol was used, the encapsulated ADH was found inactive in all the dried powders. This is presumably due to the quick crystallization of mannitol during spray drying that resulted in the impairment of enzyme protection ability in comparison to its amorphous form. Maltodextin (dextrose equivalent = 11) was used to reduce the crystallization of mannitol. The addition of maltodextrin increased ADH activity and drastically changed the powder X-ray diffractogram of the spray-dried powders.

Extraction of defatted rice bran with subcritical aqueous acetone.

Defatted rice bran extracts were obtained by subcritical treatment using aqueous acetone as extractant. Treatment with 40% (v/v) acetone at 230 °C for 5 min yielded an extract with the highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (0.274 mmol of ascorbic acid/g of bran), total carbohydrate (0.188 g/g of bran), protein (0.512 g/g of bran), and total phenolic contents (88.2 mg of gallic acid/g of bran). The effect of treatment temperature (70-230 °C) was investigated using 40% (v/v) acetone, and the extract under 230 °C treatment showed the highest levels of all the determinations described above. The extracts obtained with various concentrations of aqueous acetone were subjected to UV absorption spectra and HPLC analysis, and the results showed changes in composition and polarity. Antioxidative activity evaluated against oxidation of bulk linoleic acid of the extract obtained with 80% (v/v) acetone was higher than that not only of the extract from subcritical water treatment but also of that obtained 40% (v/v) acetone treatment.

Formation of a new crystalline form of anhydrous ß-maltose by ethanol-mediated crystal transformation.

ß-Maltose monohydrate was transformed into an anhydrous form by ethanol-mediated method under several temperatures with agitation. A new stable anhydrous form of ß-maltose (Mß(s)) was obtained, as substantiated by the X-ray diffraction patterns. Mß(s) obtained by this method presented a fine porous structure, resulting in greater specific surface area compared to those of ß-maltose monohydrate and anhydrous ß-maltose obtained by vacuum drying (Mß(h)). The crystal transformation presumably consisted of two steps: dehydration reaction from the hydrous to amorphous forms and crystal formation from the amorphous forms to the noble anhydrous form. The kinetics of these reactions were determined by thermal analysis using Jander's equation and Arrhenius plots. The overall activation energies of the dehydration reaction and the formation of anhydrous maltose were evaluated to be 100 and 90 kJ/mol, respectively.

Dissociation characteristic of the inclusion complex of cyclomaltohexaose (alpha-cyclodextrin) with 1-methylcyclopropene in response to stepwise rising relative humidity.

The dissociation of a crystalline complex of cyclomaltohexaose (alpha-cyclodextrin) and 1-methylcyclopropene has been studied in response to stepwise rising relative humidity at 50 degrees C using a dynamic vapor sorption instrument. The dissociation of the inclusion complex was monitored with a proton transfer reaction mass spectrometer. The increase in relative humidity generally triggered the complex dissociation. However, the dissociation was greatly retarded at 80% relative humidity, presumably owing to collapse of the crystalline structure. Abrupt dissociation was observed at 90% relative humidity which corresponded to complex dissolution. The changes in powder X-ray diffraction pattern of the inclusion complex during the storage period were also investigated.

Formation of spray-dried powder of S-adenosyl-L-methionine.

S-Adenosyl-L-methionine (SAM) is an essential metabolite in all living organisms. In clinical research, SAM has also been suggested as a chemotherapeutic agent in various diseases. The main problem of SAM is its instability at high temperatures, at neutral and alkaline pH, and in the presence of humidity. SAM retention in spray-dried powder was determined under various conditions of spray-drying. The highest SAM retention was obtained when maltodextrin (dextrose equivalent, DE, of 25) was used as the carrier solid with the SAM feed liquid at pH 4.0. The water content in the powder had a significant effect on the stability of SAM. SAM powder with lower water content exhibited higher stability.

Degradation kinetics of glucuronic acid in subcritical water.

The degradation kinetics of glucuronic acid (GlcA) under subcritical conditions from 160 to 200 degrees C was studied in a continuous tubular reactor. The formation of glucuronolactone (GlcL) during the treatment of GlcA in subcritical water was substantiated by ESI-TOF-MS and (1)H NMR. The degradation of GlcA consisted of the reversible conversion of GlcA to GlcL and the irreversible degradation of the two compounds. The changes in the concentrations of GlcA and GlcL with residence time could be described by first-order kinetics. Higher temperatures accelerated the degradation of GlcA, and thus resulted in rises in the pH value. The degradation reaction of GlcL under the same conditions was also investigated. The activation energy of the reverse hydrolysis of GlcA to GlcL and that of the hydrolysis of GlcL to GlcA were determined to be 88.5 and 63.2 kJ/mol respectively. The enthalpy change in the reversible conversion between GlcA and GlcL was 25.4 kJ/mol.

Improvement of antifungal activity of 10-undecyn-1-ol by inclusion complexation with cyclodextrin derivatives.

The inclusion complexation behavior between 10-undecyn-1-ol and cyclodextrin (CD) derivatives, namely, randomly methylated beta-CD (RM-beta-CD) and hydroxypropyl-beta-CD (HP-beta-CD), was studied in terms of solubility improvement, apparent stability constant, and the inclusion ratios of the resultant inclusion complexes. The aqueous solubility of 10-undecyn-1-ol was greatly improved through complexation with the CD derivatives. RM-beta-CD is comparatively more efficient in solubilizing 10-undecyn-1-ol with an apparent stability constant outstripping that of HP-beta-CD by about an order of magnitude. Comparative in vitro evaluations of the growth inhibition effects of inclusion complex solutions toward Rosellinia necatrix, a phytopathogenic fungus, were performed. In comparison with the positive control, appreciable improvements of the antifungal activity of 10-undecyn-1-ol through the addition of CD derivatives were observed visually. The improvement was evaluated in terms of area covered by the mycelia of Rosellinia necatrix and their growth rate. RM-beta-CD was proven to be more effective compared to HP-beta-CD with regard to the reduction of both fungal mycelium-covered area and growth rate constant, presumably owing to greater solubility enhancement by RM-beta-CD and thus the bioavailability of 10-undecyn-1-ol. Inclusion complexation of 10-undecyn-1-ol with CD derivatives suggests a potential means for production of an environmentally friendly 10-undecyn-1-ol-based fungicide to counteract R. necatrix.

Kinetic study of thermally stimulated dissociation of inclusion complex of 1-methylcyclopropene with alpha-cyclodextrin by thermal analysis.

The thermally stimulated dissociation of the inclusion complex of 1-methylcyclopropene (1-MCP) with alpha-cyclodextrin (alpha-CD) in solid state was studied by means of thermogravimetry (TG) and differential scanning calorimetry (DSC). The mass loss of 1-MCP/alpha-CD inclusion complex occurs in four separated phases with the thermal dissociation of the inclusion complex and release of 1-MCP taking place in the second phase between 90 and 230 degrees C. The kinetic parameters of the dissociation reaction (the apparent activation energy of dissociation, E(D), the reaction order of thermal dissociation, n, and the pre-exponential factor, k0) were evaluated. The dissociation reaction was satisfactorily described by the unimolecular decay law, where the reaction order, n = 1. The effect of the molar ratio of 1-MCP to alpha-CD (inclusion ratio) in the inclusion complex on the temperature dependence of the dissociation reaction was also studied. The E(D) decreased with increasing inclusion ratio indicating higher complex stability at lower inclusion ratios. The extrapolation of the E(D) of the inclusion complexes with different inclusion ratios to 1 mol 1-MCP/mol alpha-CD yielded the "true" E(D) of 20.9 +/- 2.8 and 18.1 +/- 0.2 kJ/mol for TG and DSC, respectively. The "true" ln k(0TG) and the "true" ln k(0DSC) were also determined by extrapolation, yielding values of +4.5 +/- 1.0 and -0.3 +/- 0.3, respectively.

Kinetics of molecular encapsulation of 1-methylcyclopropene into alpha-cyclodextrin.

1-methylcyclopropene (1-MCP), an ethylene inhibiting regulator, is commercially available in the form of an inclusion complex with alpha-cyclodextrin (alpha-CD). In this study, molecular encapsulation of gaseous 1-MCP into aqueous alpha-CD was investigated in a closed, agitated vessel with a flat gas-liquid interface. Molecular encapsulation of gaseous 1-MCP by alpha-CD is a simultaneous two-step reaction which involves the aqueous dissolution of gaseous 1-MCP and the encapsulation of the dissolved molecules by alpha-CD. The kinetics and mechanism of molecular encapsulation were analyzed based on the depletion rate of 1-MCP in the headspace of the vessel. The encapsulation rates could be explained quantitatively by the gas absorption theory with a pseudo-first-order reaction between 1-MCP and alpha-CD. The negative value of the calculated apparent activation energy of encapsulation (-24.4 kJ/mol) implied the significant effect of exothermic aqueous dissolution of 1-MCP. An encapsulation temperature of 15 degrees C was optimal; at this temperature, the highest 1-MCP yield and best inclusion ratio of inclusion complex were obtained. Changes in the X-ray diffraction pattern suggested that the crystal lattice structure of alpha-CD was altered upon inclusion of 1-MCP.