Synthesis of imines from amines in aliphatic alcohols on Pd/ZrO2 catalyst under ambient conditions

Synthesis of imines from amines and aliphatic alcohols (C1–C6) in the presence of base on supported palladium nanoparticles has been achieved for the first time. The catalytic system shows high activity and selectivity in open air at room temperature. As an example of the isostructural Ln3Sb3Co2O14 (Ln: La, Pr, Nd, Sm—Ho) series with an ordered pyrochlore structure, the La variant is prepared by a citrate complex method employing stoichiometric amounts of La(NO3)3, Co(NO3)2, and Sb tartrate together with citric acid with a metal/citrate molar ratio of 1:2

Sexual selection in a tropical fruit fly : role of a plant derived chemical in mate choice

The specific mechanisms by which selective pressures affect individuals are often difficult to resolve. In tephritid fruit flies, males respond strongly and positively to certain plant derived chemicals. Sexual selection by female choice has been hypothesized as the mechanism driving this behaviour in certain species, as females preferentially mate with males that have fed on these chemicals. This hypothesis is, to date, based on studies of only very few species and its generality is largely untested. We tested the hypothesis on different spatial scales (small cage and seminatural field-cage) using the monophagous fruit fly, Bactrocera cacuminata. This species is known to respond to methyl eugenol (ME), a chemical found in many plant species and one upon which previous studies have focused. Contrary to expectation, no obvious female choice was apparent in selecting ME-fed males over unfed males as measured by the number of matings achieved over time, copulation duration, or time of copulation initiation. However, the number of matings achieved by ME-fed males was significantly greater than unfed males 16 and 32 days after exposure to ME in small cages (but not in a field-cage). This delayed advantage suggests that ME may not influence the pheromone system of B. cacuminata but may have other consequences, acting on some other fitness consequence (e.g., enhancement of physiology or survival) of male exposure to these chemicals. We discuss the ecological and evolutionary implications of our findings to explore alternate hypotheses to explain the patterns of response of dacine fruit flies to specific plant-derived chemicals.

Cough-generated aerosols of Pseudomonas aeruginosa and other Gram Negative Bacteria from cystic fibrosis patients.

Background: Pseudomonas aeruginosa is the most common bacterial pathogen in cystic fibrosis (CF) patients. Current infection control guidelines aim to prevent transmission via contact and respiratory droplet routes and do not consider the possibility of airborne transmission. We hypothesized that with coughing, CF subjects produce viable, respirable bacterial aerosols. Methods: Cross-sectional study of 15 children and 13 adults with CF, 26 chronically infected with P. aeruginosa. A cough aerosol sampling system enabled fractioning of respiratory particles of different size, and culture of viable Gram negative non-fermentative bacteria. We collected cough aerosols during 5 minutes voluntary coughing and during a sputum induction procedure when tolerated. Standardized quantitative culture and genotyping techniques were used. Results: P. aeruginosa was isolated in cough aerosols of 25 (89%) subjects of whom 22 produced sputum samples. P. aeruginosa from sputum and paired cough aerosols were indistinguishable by molecular typing. In 4 cases the same genotype was isolated from ambient room air. Approximately 70% of viable aerosols collected during voluntary coughing were of particles ≤ 3.3 microns aerodynamic diameter. P. aeruginosa, Burkholderia cenocepacia Stenotrophomonas maltophilia and Achromobacter xylosoxidans were cultivated from respiratory particles in this size range. Positive room air samples were associated with high total counts in cough aerosols (P=0.003). The magnitude of cough aerosols were associated with higher FEV1 (r=0.45, P=0.02) and higher quantitative sputum culture results (r=0.58, P=0.008). Conclusion: During coughing, CF patients produce viable aerosols of P. aeruginosa and other Gram negative bacteria of respirable size range, suggesting the potential for airborne transmission.

Investigations into the analytical applications and fundamental chemistry of the chemiluminescent reactions of Tris(2,2'-bipyridyl)ruthenium(III) with certain Papaver Somniferum alkaloids and other related compounds

The reaction of tris(2,2’-bipyridyl)ruthenium(III) (Ru(bipy) ₃³⁺) with various analytes to generate chemiluminescence has been well documented. This investigation sought to undertake a chemiluminometic study of the reactions of Ru(bipy) ₃³⁺ with selected Papaver Somniferum alkaloids and specifically synthesised phenethylamines. The investigation, based on a kinetic study, primarily addressed the effect of varying reaction conditions (pH) on Ru(bipy) ₃³⁺ chemiluminescence production. To monitor these reactions, a batch chemiluminometer was specifically designed, fabricated and automated to conduct an extensive study on the selected compounds of interest. The instrumentation incorporated a custom built reaction cell and comprised an ‘on-line’ sample preparation system with which calibration standards could be automatically prepared. The instrumentation provided both time-independent (peak area) and time-dependent (kinetic profile) information. A novel approach to the stabilisation of Ru(bipy) ₃³⁺ as a chemiluminescencent reagent was also investigated and a recirculating system was employed with the batch chemiluminometer to provide a stable supply of Ru(bipy) ₃³⁺. Codeine, thebaine and 6-methoxy-codeine were the Papaver Somniferum alkaloids selected for this study and several N-methylated and N,N-dimethylated phenethylamines and methoxy-substituted phenetheylamines were also synthesised to investigate the affect of pH on the chemiluminescence emission efficiency. The versatility of the batch chemiluminometer facilitated the kinetic study of numerous analytes over a broad pH range. The exemplary performance of the chemiluminometer as an analytical instrument, was demonstrated by the calibration functions, based on peak area data, which exhibited excellent linearity and sensitivity. The estimated detection limits (3s) for the selected alkaloids were in the range 2 x 10^-9 M to 7 x 10^-9 at pH 5.0 and above, which compared favourably to detection limits for the same compounds determined using FIA. Relative standard deviations (n=5) for peak areas ranged between 1% to 5% with a mean of 3.1% for all calibration standards above 2.5 x 10^-8 M. Correlation between concentration and peak area, irrespective of pH and analyte was excellent, with all but two calibration functions having r-squared values greater than 0.990. The analytical figures of merit exemplified the precision and robustness of the reagent delivery and ‘on-line’ sample preparation, as well as the sensitivity of the system. The employment of the chemiluminometer for the measurement of total chemiluminescence emission (peak area) was in itself a feasible analytical technique, which generated highly reproducible and consistent data. Excellent analytical figures of merit, based on peak area, were similarly achieved for the phenethylamines. The effects of analyte structure on chemiluminescence activity was also investigated for the alkaloids and the phenethylamines. Subtle structural variations between the three alkaloids resulted in either a moderately reduced or enhanced total emission that was two or three fold difference only. A significant difference in reaction kinetics was observed between thebaine and codeine/6-methoxy-codeine, which was dependent upon pH. The time-dependent data, namely the observed rate constants for the initial rise in intensity and for the subsequent decay rate, were obtained by fitting a mathematical function (based on the postulated reaction mechanism) to the raw data. The determination of these rate constants for chemiluminescence reactions highlighted the feasibility for utilising such measurements for quantitative analytical applications. The kinetic data were used to discriminate between analyte responses in order to determine the concentrations of individual analytes in a binary mixture. A preliminary, multi-component investigation performed on a binary mixture of codeine and 6-methoxy-codeine (1:1) successfully determined the concentrations of these individual components using such rate constant measurements. Consequently, variations in kinetics resulted in a significant difference between the relative chemiluminescence response based on peak area measurements and the relative response base on peak height measurements obtained using FIA. With regards to the observed reactivity of secondary amines and tertiary amines, chemiluminescence peak area determinations confirmed the vital role of pH on reaction efficiency, which was governed by structural features and kinetics. The tertiary amines investigated generally produced a greater emission under acidic conditions than the corresponding secondary amines. However, the measured chemiluminescence responses were highly dependent upon pH, with similar peak areas obtained for both amine groups under slightly alkaline conditions.

A new imidazole alkaloid and other constituents from Pilocarpus grandiflorus and their antifungal activity

The stems of Pilocarpus grandiflorus have afforded the new imidazole alkaloid 4,6-dehydro-1,2,4,5-tetrahydro-2,5-dioxopilocarpine in addition to the 17 known compounds germanicol, β-amiryn, ocotillone, stigmast-4-en-3-one, 3β-hydroxy-stigmast-5-en-7-one, 6β-hydroxy-stigmast-4-en-3-one, β-sitosterol, scopoletin, 3-(1′,1′-dimethylallyl)-scopoletin, elisin, dictamine, 4-methoxy-2-quinolone, platydesmine, syringaresinol, syringaldehyde, syringic acid and vanillic acid. Their structures were elucidated on the basis of chemical and spectroscopic evidence. The phenolic compounds vanillic acid and syringaldehyde and the furoquinoline alkaloid platydesmine exhibited antifungal activity against Leucoagaricus gongylophorus, the symbiotic fungus of leaf-cutting ants (Atta sexdens rubropilosa). © 2005 Verlag der Zeitschrift für Naturforschung.

Calbistrin E and two other new metabolites from an Australian isolate of Penicillium striatisporum

An Australian isolate of Penicillium striatisporum collected near Shalvey, New South Wales, exhibited selective antifungal activity against Candida albicans versus Saccharomyces cerevisiae. Bioassay-directed fractionation yielded members of the rare class of fungal metabolites known as the calbistrins. These included a new example of this structure class, calbistrin E (1), as well as the known polyenes calbistrin C (2) and deformylcalbistrin A (3). Also recovered from P. striatisporum were new triene and butenolide acids, striatisporin A (4) and striatisporolide A (5), together with the known fungal metabolites versiol (6) and (+)-hexylitaconic acid (7). Structures for all metabolites were determined by detailed spectroscopic analysis.

Comparison of ultrafine particle release from hardcopy devices in emission test chambers and office rooms

The release of ultrafine particles (UFP) from laser printers and office equipment was analyzed using a particle counter (FMPS; Fast Mobility Particle Sizer) with a high time resolution, as well as the appropriate mathematical models. Measurements were carried out in a 1 m³ chamber, a 24 m³ chamber and an office. The time-dependent emission rates were calculated for these environments using a deconvolution model, after which the total amount of emitted particles was calculated. The total amounts of released particles were found to be independent of the environmental parameters and therefore, in principle, they were appropriate for the comparison of different printers. On the basis of the time-dependent emission rates, “initial burst” emitters and constant emitters could also be distinguished. In the case of an “initial burst” emitter, the comparison to other devices is generally affected by strong variations between individual measurements. When conducting exposure assessments for UFP in an office, the spatial distribution of the particles also had to be considered. In this work, the spatial distribution was predicted on a case by case basis, using CFD simulation.

Characterization of commercial double-walled carbon nanotube material : composition, structure, and heat capacity

A purified commercial double-walled carbon nanotube (DWCNT) sample was investigated by transmission electron microscopy (TEM), thermogravimetry (TG), and Raman spectroscopy. Moreover, the heat capacity of the DWCNT sample was determined by temperature-modulated differential scanning calorimetry in the range of temperature between -50 and 290 °C. The main thermo-oxidation characterized by TG occurred at 474 °C with the loss of 90 wt% of the sample. Thermo-oxidation of the sample was also investigated by high-resolution TG, which indicated that a fraction rich in carbon nanotube represents more than 80 wt% of the material. Other carbonaceous fractions rich in amorphous coating and graphitic particles were identified by the deconvolution procedure applied to the derivative of TG curve. Complementary structural data were provided by TEM and Raman studies. The information obtained allows the optimization of composites based on this nanomaterial with reliable characteristics.

Long-term trends in fine particle number concentrations in the urban atmosphere of Brisbane : the relevance of traffic emissions and new particle formation

The measurement of submicrometre (< 1.0 m) and ultrafine particles (diameter < 0.1 m) number concentration have attracted attention since the last decade because the potential health impacts associated with exposure to these particles can be more significant than those due to exposure to larger particles. At present, ultrafine particles are not regularly monitored and they are yet to be incorporated into air quality monitoring programs. As a result, very few studies have analysed their long-term and spatial variations in ultrafine particle concentration, and none have been in Australia. To address this gap in scientific knowledge, the aim of this research was to investigate the long-term trends and seasonal variations in particle number concentrations in Brisbane, Australia. Data collected over a five-year period were analysed using weighted regression models. Monthly mean concentrations in the morning (6:00-10:00) and the afternoon (16:00-19:00) were plotted against time in months, using the monthly variance as the weights. During the five-year period, submicrometre and ultrafine particle concentrations increased in the morning by 105.7% and 81.5% respectively whereas in the afternoon there was no significant trend. The morning concentrations were associated with fresh traffic emissions and the afternoon concentrations with the background. The statistical tests applied to the seasonal models, on the other hand, indicated that there was no seasonal component. The spatial variation in size distribution in a large urban area was investigated using particle number size distribution data collected at nine different locations during different campaigns. The size distributions were represented by the modal structures and cumulative size distributions. Particle number peaked at around 30 nm, except at an isolated site dominated by diesel trucks, where the particle number peaked at around 60 nm. It was found that ultrafine particles contributed to 82%-90% of the total particle number. At the sites dominated by petrol vehicles, nanoparticles (< 50 nm) contributed 60%-70% of the total particle number, and at the site dominated by diesel trucks they contributed 50%. Although the sampling campaigns took place during different seasons and were of varying duration these variations did not have an effect on the particle size distributions. The results suggested that the distributions were rather affected by differences in traffic composition and distance to the road. To investigate the occurrence of nucleation events, that is, secondary particle formation from gaseous precursors, particle size distribution data collected over a 13 month period during 5 different campaigns were analysed. The study area was a complex urban environment influenced by anthropogenic and natural sources. The study introduced a new application of time series differencing for the identification of nucleation events. To evaluate the conditions favourable to nucleation, the meteorological conditions and gaseous concentrations prior to and during nucleation events were recorded. Gaseous concentrations did not exhibit a clear pattern of change in concentration. It was also found that nucleation was associated with sea breeze and long-range transport. The implications of this finding are that whilst vehicles are the most important source of ultrafine particles, sea breeze and aged gaseous emissions play a more important role in secondary particle formation in the study area.