Controlled release from zein matrices: Interplay of drug hydrophobicity and pH

Purpose: In earlier studies, the corn protein zein is found to be suitable as a sustained release agent, yet the range of drugs for which zein has been studied remains small. Here, zein is used as a sole excipient for drugs differing in hydrophobicity and isoelectric point: indomethacin, paracetamol and ranitidine. Methods: Caplets were prepared by hot-melt extrusion (HME) and injection moulding (IM). Each of the three model drugs were tested on two drug loadings in various dissolution media. The physical state of the drug, microstructure and hydration behaviour were investigated to build up understanding for the release behaviour from zein based matrix for drug delivery. Results: Drug crystallinity of the caplets increases with drug hydrophobicity. For ranitidine and indomethacin, swelling rates, swelling capacity and release rates were pH dependent as a consequence of the presence of charged groups on the drug molecules. Both hydration rates and release rates could be approached by existing models. Conclusion: Both the drug state as pH dependant electrostatic interactions are hypothesised to influence release kinetics. Both factors can potentially be used factors influencing release kinetics release, thereby broadening the horizon for zein as a tuneable release agent

Moving I`iwi (Vestiaria coccinea) as a Surrogate for Future Translocations of Endangered `Akohekohe (Palmeria dolei)

Translocations often play an important role in the recovery of endangered species. To assess feasibility for translocation of endangered `Akohekohe (Palmeria dolei), we conducted an experimental translocation of I`iwi (Vestiaria coccinea) from east to west Maui. Mist-netting, veterinary screening of candidate birds, and helicopter transport of healthy I`iwi were successful, resulting in no injuries or mortalities. Translocated birds were assigned to two types of release. Hard release birds were radio tagged and released on the day of translocation. In contrast, soft release birds were held in large cages for 7 days and fed artificial nectar. During holding soft release I`iwi feeding rates, fecal production, and mass were monitored. Soft release birds suffered 33% mortality during the holding period. At the end of the holding period, soft release survivors were outfitted with a radio transmitter and released. All translocated I`iwi were followed by radio telemetry for an average of 21 days. Once released, soft release birds showed higher rates of movement, possibly reflecting conflict with established hard released I`iwi. Our results suggest that translocation efforts for wild `Akohekohe will be successful if hard release protocols are followed

A Comparison of Sensitivity Metrics for Two-Stage Ignition Behavior in Rapid Compression Machines

A rapid compression machine (RCM) multi-zone model is used to simulate the ignition of primary reference fuel (PRF) mixtures that exhibit two-stage ignition behavior. Sensitivity coefficients for each reaction in the PRF mechanism are calculated from four different metrics: (1) first-stage energy release, (2) first-stage pressure rise, (3) first-stage ignition delay time, and (4) total ignition delay time. The sensitivity coefficients are used to provide four unique rankings, and the rankings are compared using Spearman’s rank correlation coefficient. Special emphasis is given to comparing the rankings based on first-stage energy release and total ignition delay time. The level of agreement between these two rankings is shown to depend on the reaction conditions. Simulation cases with high peak heat release rates during the first stage of ignition tend to exhibit disagreement in the rankings, indicating that new kinetic information can be obtained by studying first stage energy release in addition to total ignition delay time. Simulations show that the high peak heat release rates are associated with energy release across a broad range of temperatures (range can be in excess of 100 K even for lean conditions). This distribution leads to a discrepancy between sensitivity coefficients calculated for the total ignition delay time and the first-stage energy release. Sensitivity coefficients for the total ignition delay time are characterized by reactivity at the highest temperatures in the RCM, while sensitivity coefficients for the first-stage energy release are characterized by reactivity across the full range of temperatures in the RCM

Evaluation of Three Trap Types and Five Lures for Monitoring \u3ci\u3eHylurgus Ligniperda\u3c/i\u3e (Coleoptera: Scolytidae) and Other Local Scolytids in New York

Hylurgus ligniperda (Coleoptera: Scolytidae) is a pine (Pinus spp.) pest native to Eurasia and northern Africa. In December 2000, an established population of H. ligniperda was discovered in Monroe County, New York. When surveys were initiated to determine the distribution of H. ligniperda, questions arose regarding the most effective trap and lure for survey purposes. We conducted a study in April-May 2001 to compare the effectiveness of commercially available scolytid traps and lures for attracting and capturing H. ligniperda. Traps tested included: 1) 12-unit Lindgren funnel trap, 2) Intercept panel trap, and 3) Theysohn slot-trap. Lures tested included: 1) α-pinene high release (750 mg/day) and ethanol (280 mg/ day), 2) α-pinene low release (300 mg/day) and ethanol, 3) β-pinene high release (2000 mg/day) and ethanol, 4) α-pinene low release, and 5) the “exotic bark beetle lure” [ipsdienol (0.15 mg/day), cis-verbenol (0.35 mg/day), and methylbutenol (10 mg/day)]. All three trap designs captured H. ligniperda, however, the Lindgren funnel trap caught significantly higher numbers. Capture rates of Tomicus piniperda (Coleoptera: Scolytidae) and Hylastes opacus were highest in Lindgren funnel traps; whereas Orthotomicus caelatus collections were highest in Theysohn traps. Capture rates of Ips grandicollis and Xyleborinus saxeseni did not vary significantly among trap types. Behavioral differences among scolytid species such as visual stimuli, flight and landing behavior, and host selection may explain some of these differences. Lures containing α-pinene or β-pinene and ethanol were most attractive to H. ligniperda adults, with ethanol and high-release α-pinene attracting the highest numbers in absolute terms. The exotic bark beetle lure was the least attractive lure to H. ligniperda. Attractiveness of the lures tested varied significantly for other Scolytidae, including Dendroctonus valens, H. opacus, Ips calligraphus, I. grandicollis, I. pini, O. caelatus, T. piniperda, and X. saxeseni. These differences likely were due to variation in lure release rates, host preferences, and/or species-specific pheromone attraction

Determining whether estimated spore release rates for Aspergillus fumigatus are compatible with their measured growth rates in composting systems

The composting process like other waste management activities has the potential to generate large concentrations of bioaerosols which can be widely dispersed into the surrounding environment. There has been considerable interest in the literature of the effect of bioaerosols and in particular Aspergillus fumigatus on the health of plant operators and those living in close proximity to composting plants (Olver, 1994; Fischer et al., 1999; Fischer et al., 2000; Bunger et al., 200). Although bioaerosols can be generated through a range of operational procedures it has also been suggested that large numbers of Aspergillus fumigatus spores can be emitted from static compost piles through the action of natural air movements across the surface of the biodegrading material. Through the use of a portable wind tunnel apparatus researchers have determined the rate of emission of Aspergillus fumigatus spores as a result of air movement across the surface of the material (Taha et al., 2004; 2005; 2006 & 2007). The aim of this work was to use controlled laboratory experiments using compost samples and Aspergillus fumigatus spores to determine the sporulation rate of Aspergillus fumigatus. Using this data it would then be possible to verify whether bioaerosol emission rates from static compost windrows calculated and quoted in the literature can in fact be maintained over longer time periods. A series of experiments were carried out using Aspergillus fumigatus spores on agar plates and small samples of green waste compost to determine the number of spores that could be generated by each existing spore over a seven day period. From the experiments the sporulation rate determined from the agar plates varied with averages of either 4.48x104 or 2.83 spores/day depending upon the date set used and from the compost experiments it was 1.33 spores/day. Using this data and making a number of assumptions for moisture content (50%), bulk density (650 kg/m3) and the wind penetration depth (10-25mm) the potential release rates were calculated. The data from the agar experiments yielded a potential release rate at 10mm up to 5 orders of magnitude in excess of that quoted by Taha et al. (2004 & 2005. Using the trimmed data set the agar release figures are between 6.17 x 103 and 1.23 x 104 cfu/m2/s depending upon the wind penetration depth used and are comparable to those quoted in the literature. The release rate calculated using the compost experiments was slightly lower than the agar 2 data and consequently the release rates even at a wind penetration depth of 25mm are just outside the range quoted by Taha et al. (2004 & 2005). Although the data presented in this paper were determined from controlled laboratory experiments they show that it is possible for Aspergillus fumigatus to generate spores at a sufficient rate to allow the release of significant numbers of spores. The calculated sporulation rates would allow spores to be released at the rates quoted in the literature and suggest that the fugitive release rates quoted in the literature would be able to be maintained over long periods of time. However it is recognised that the data is affected greatly by the assumptions one makes, in particular the existing concentration of Aspergillus fumigatus. Despite the limitations the original intention of the work was to attempt to establish the long term applicability of the fugitive release rates for Aspergillus fumigatus from green waste compost quoted in the literature and it has achieved this objective

Formation of porous membranes for drug delivery systems

Highly crystalline porous hollow poly (-lactide) (PLLA) fibres suitable for the delivery of various drugs were obtained using a dry-wet spinning process. The pore structure of the fibres could be regulated by changing the spinning systems and spinning conditions. Using the spinning system PLLA-dioxane-water, fibres with a dense toplayer and a spongy sublayer were obtained. The spinning system PLLA-chloroform/toluene-methanol yielded fibres with a very open porous structure. The membrane formation of the former system probably occurs by liquid-liquid demixing followed by crystallization of the polymer rich phase. In the membrane formation process of the spinning system, PLLA-chloroform/toluene-methanol crystallization probably plays a dominant role. The membrane formation process will be related to basic principles of phase separation. The fibres are suitable for the long term zero order delivery of the contraceptive 3-ketodesogestrel and the short term zero order delivery of the cytostatic agent, cisplatin. The drugs are released by dissolution of the drug crystals in the fibre core followed by diffusion through the membrane structure. Short term release of adriamycin could be obtained through an adsorption-desorption mechanism. The pore structures of the fibres have a large influence on the release rates of the drugs investigated. When fibres with dense toplayers were used, low release rates of drugs were observed whereas fibres with well interconnected pore structures over the fibre wall showed very high release rates

A study of energy release in rocket propellants by a projectile impact method Annual report, 10 May 1967 - 9 May 1968

Experimental measurement of rates of energy release in solid propellants subjected to strong shock waves from projectile impac

Magnetic flares in the protoplanetary nebula and the origin of meteorite chondrules

This study proposes and analyzes a model for the chondrule forming heating events based on magnetohydrodynamic flares in the corona of the protoplanetary nebula which precipitate energy in the form of energetic plasma along magnetic field lines down toward the face of the nebula. It is found that flare energy release rates sufficient to melt the prechondrular matter, leading to the formation of the chondrules, can occur in the tenuous corona of a protostellar disk. Energy release rates sufficient to achieve melting require that the ambient magnetic field strength be in the range that has been inferred separately from independent meteorite remanent magnetization studies

Disruptant Effects of 4-Allylanisole and Verbenone on \u3ci\u3eTomicus Piniperda\u3c/i\u3e (Coleoptera: Scolytidae) Response to Baited Traps and Logs

We assessed the inhibitory effects of the host compound 4-allylanisole (release rates = 1 and 2 mg/d in 1994, and 1 and 10 mg/d in 2001) on the response of the pine shoot beetle, Tomicus piniperda (L.), adults to funnel traps baited with the attractant host compound α-pinene (release rate = 150 mg/d) in two pine Christmas tree plantations in Michigan in spring 1994 and two other plantations in spring 2001. In three of the four plantations, all doses of 4- allylanisole significantly reduced T. piniperda attraction to α-pinene-baited traps by 46 to 76%. We also tested the inhibitory effect of the antiaggregation pheromone verbenone (release rates = 2 and 4 mg/d) on T. piniperda attack density on pine bolts (average bolt length was 62 cm and diameter was 19 cm) at three sites (two pine forest stands and one Christmas tree plantation) in Michigan in 1994. Verbenone significantly reduced T. piniperda attack density by 37 to 60% at the two pine stands, but not at the Christmas tree plantation