Detection of Gravitational Redshift on the Solar Disk by Using Iodine-Cell Technique

With an aim to examine whether the predicted solar gravitational redshift can be observationally confirmed under the influence of the convective Doppler shift due to granular motions, we attempted measuring the absolute spectral line-shifts on a large number of points over the solar disk based on an extensive set of 5188-5212A region spectra taken through an iodine-cell with the Solar Domeless Telescope at Hida Observatory. The resulting heliocentric line shifts at the meridian line (where no rotational shift exists), which were derived by finding the best-fit parameterized model spectrum with the observed spectrum and corrected for the earth's motion, turned out to be weakly position-dependent as ~ +400 m/s near the disk center and increasing toward the limb up to ~ +600 m/s (both with a standard deviation of sigma ~ 100 m/s). Interestingly, this trend tends to disappear when the convectiveshift due to granular motions (~-300 m/s at the disk center and increasing toward the limb; simulated based on the two-component model along with the empirical center-to-limb variation) is subtracted, finally resulting in the averaged shift of 698 m/s (sigma = 113 m/s). Considering the ambiguities involved in the absolute wavelength calibration or in the correction due to convective Doppler shifts (at least several tens m/s, or more likely up to <~100 m/s), we may regard that this value is well consistent with the expected gravitational redshift of 633 m/s.Comment: 28 pages, 12 figures, electronic materials as ancillary data (table3, table 4, ReadMe); accepted for publication in Solar Physic

Laboratory Evaluation of Novaluron as a Development Site Treatment for Controlling Larval Horn Flies, House Flies, and Stable Flies (Diptera: Muscidae)

A granular formulation of novaluron (Novaluron 0.2G, 0.2% [AI]), a newer benzoylphenyl urea insecticide, was evaluated for its efficacy in controlling the larval stage of horn flies, Haematobia irritans (L.); house flies, Musca domestica L.; and stable flies, Stomoxys calcitrans (L.), in cow manure. Various rates and insecticide placement locations (top, middle, and bottom of manure) were evaluated in this study and all combinations of these variables reduced adult emergence of all three species when compared with the untreated controls. The presence of deformed pupae indicated that novaluron had an insect growth regulator effect on the developing fly y larvae. Top, middle, or bottom application rates of 0.125, 0.195, 0.25, and 0.375 g novaluron onto manure samples, reduced adult horn fly y emergence by \u3e90%. Middle and bottom application rates of 0.195, 0.25, and 0.375 g novaluron reduced adult house fly y emergence \u3e93%. All rates and placement combinations resulted in \u3e98% reduction of adult stable fly emergence. The level of control efficacy observed against these three fly species along with the ease of use of a granular formulation, make this product an ideal candidate for use in an integrated livestock pest management program

Biological soil crust and vascular plant interactions in Western Myall (Acacia papyrocarpa) open woodland in South Australia

Aim: Biological soil crust (BSC) is a key component of arid environments and plays a major role in determining ecological structure and function. Our research aim was to examine several mechanisms that contribute to BSC–plant interactions at species and community levels, to increase our understanding of plant community dynamics. Location: Yellabinna Regional Reserve, South Australia (30°50′17.99″ S, 132°12′10.37″ E). Methods: We used seed extraction techniques to examine soil seed banks beneath patches with and without BSC, and field and glasshouse experiments to study the effects of crust presence and disturbance on seedling emergence and survival. We also explored the influence of chemical leachates from BSC on seed germination. Results: Biological soil crust plays a pivotal role in influencing spatial patterns in soil seed bank composition. Our results showed less propagules accumulate in soils beneath crust when compared with patches without crust, and that propagule size is a contributing factor to determining their distribution between patch types. We found that late‐stage BSC physically inhibited seedling emergence, which increased when the BSC was disturbed in field experiments. Low seedling survivorship in both patch types suggests that although BSC may suppress recruitment in favourable years, it is low precipitation levels that have the over‐riding impact on recruitment success. Finally, leachates from late‐stage BSC were found to inhibit germination in three annual plant species, whilst early‐stage BSC accelerated germination in one annual plant. This clearly shows that leachate effects on seed germination vary according to plant species and crust successional stage. Conclusion: Overall, we identified several mechanisms through which BSC has complex effects on the annual and short‐lived perennial plant guilds of arid lands. These mechanisms contribute to species diversity through the creation of spatial heterogeneity in soil seed bank structure and emergence opportunities.Emma K. Steggles, José M. Facelli, Phillip J. Ainsley, Leanne M. Poun

Polymer-protein conjugates from ω-aldehyde endfunctional poly(N-vinylpyrrolidone) synthesised via xanthate-mediated living radical polymerisation

Aldehyde ω-endfunctional poly(N-vinylpyrrolidone) was synthesised via quantitative conversion of a xanthate endfunctional precursor obtained via RAFT-mediated polymerisation. © The Royal Society of Chemistry.Articl

In-situ NMR spectroscopy for probing the efficiency of RAFT/MADIX agents

The experimental evidence of selective initialization of poorly stabilized monomers in reversible addition fragmentation chain transfer (RAFT) mediated living radical polymerization was reported. Xanthate chain transfer agents (CTA) were used to mediate the polymerization of N-vinylpyrrolidone (NVP) and vinyl acetate (VAc). In-situ H NMR spectroscopy was performed to follow the concentrations of xanthate and monomer and to identify the nonradical species in the RAFT mechanism. Various xanthates were screened and a direct relationship between a xanthate-monomer system which gives fast and selective initialization and a high degree of control over the molar mass distribution of the polymer was found. The results show that in-situ H NMR spectroscopy can quantitatively probe the mechanism of initialization involved in the transformation of a CTA into a dormant oligomeric chain.Articl

In-situ NMR spectroscopy for probing the efficiency of RAFT/MADIX agents

Communication to the Edito

Unexpected reactions associated with the xanthate-mediated polymerization of N-vinylpyrrolidone

The monomer N-vinylpyrrolidone (NVP) undergoes side reactions in the presence of R group functional xanthates and impurities. The fate of the monomer NVP and a selection of six O-ethyl xanthates during xanthate-mediated polymerization were studied via NMR spectroscopy. A high number of by-products were identified. Significant side reactions affecting NVP include the formation of an unsaturated dimer and hydration products in bulk or in solution in C 6D6. In addition, the xanthate adjacent to a NVP unit was found to undergo elimination at moderate temperature (60-70°C), resulting in unsaturated species and the formation of new xanthate species. The presence of the chlorinated compound α-chlorophenyl acetic acid, ethyl ester, a precursor in the synthesis of the xanthate S-(2-ethyl phenylacetate) O-ethyl xanthate, resulted in a dramatic increase in the rate of side reactions such as unsaturated dimer formation and a high ratio of unsaturated chain ends. The conditions for the occurrence of such side reactions are discussed in this article, with relevance to increasing the control over the polymerization kinetics, endgroup functionality, and control over the molar mass distribution. © 2008 Wiley Periodicals, Inc.Articl

Unexpected reactions associated with the xanthate-mediated polymerization of N-vinylpyrrolidone

The monomer N-vinylpyrrolidone (NVP) undergoes side reactions in the presence of R group functional xanthates and impurities. The fate of the monomer NVP and a selection of six O-ethyl xanthates during xanthate-mediated polymerization were studied via NMR spectroscopy. A high number of by-products were identified. Significant side reactions affecting NVP include the formation of an unsaturated dimer and hydration products in bulk or in solution in C6D6. In addition, the xanthate adjacent to a NVP unit was found to undergo elimination at moderate temperature (60-70 °C), resulting in unsaturated species and the formation of new xanthate species. The presence of the chlorinated compound -chlorophenyl acetic acid, ethyl ester, a precursor in the synthesis of the xanthate S-(2-ethyl phenylacetate) O-ethyl xanthate, resulted in a dramatic increase in the rate of side reactions such as unsaturated dimer formation and a high ratio of unsaturated chain ends. The conditions for the occurrence of such side reactions are discussed in this article, with relevance to increasing the control over the polymerization kinetics, endgroup functionality, and control over the molar mass distribution. © 2008 Wiley Periodicals