Silver Engineered Nanomaterials and Ions Elicit Species-Specific O\u3csub\u3e2\u3c/sub\u3e Consumption Responses in Plant Growth Promoting Rhizobacteria

Metal containing engineered nanomaterials (ENMs) are now commonly used in various industrial and commercial applications. Many of these materials can be transformed during waste water treatment and ultimately enter terrestrial ecosystems via agriculturally applied biosolids. It is unclear how agriculturally important soil microbes will be affected by exposure to environmentally relevant, sublethal concentrations of ENMs and their transformation products (i.e., ions, aggregates, etc.). A method was developed, which puts O2 consumption responses in terms of viability, and tested by examining the toxic effects of Ag+, Zn2+, and Ni2+ ions on the plant growth promoting rhizobacterium (PGPR) Bacillus amyloliquefaciens GB03. The method was then used to examine the toxicity of Ag+, as-synthesized polyvinylpyrrolidone-coated silver ENM (PVP-AgENMs), and 100% sulfidized AgENM on B. amyloliquefaciens GB03, and two additional PGPRs Sinorhizobium meliloti 2011, and Pseudomonas putida UW4. S. meliloti was found to have the highest LC50 for Ag+ and PVP-AgENMs (6.6 and 207 μM, respectively), while B. amyloliquefaciens and P. putida exhibited LC50\u27s for Ag+ and PVP-AgENMs roughly half those observed for S. meliloti. The authors observed species-specific O2 consumption responses to ENM and ion exposure. PVP-AgENMs were less toxic than ions on a molar basis, and abiotic dissolution likely explains a significant portion of the observed toxic responses. Our results suggest microbes may exhibit distinct metabolic responses to metal and ENM exposure, even when similar LC50\u27s are observed. These findings together illustrate the importance of understanding species-specific toxic responses and the utility of examining O2 consumption for doing so

The Membership and Distance of the Open Cluster Collinder 419

The young open cluster Collinder 419 surrounds the massive O star, HD 193322, that is itself a remarkable multiple star system containing at least four components. Here we present a discussion of the cluster distance based upon new spectral classifications of the brighter members, UBV photometry, and an analysis of astrometric and photometric data from the UCAC3 and 2MASS catalogs. We determine an average cluster reddening of E(B-V)=0.37 +- 0.05 mag and a cluster distance of 741 +- 36 pc. The cluster probably contains some very young stars that may include a reddened M3 III star, IRAS~20161+4035

A Tribute to Justice Byron R. White

Of 107 Justices in 205 years, only twelve have served longer than thirty years, and every long-serving Justice has made a substantial contribution to the institution - offering a steady and dedicated response to the judicial challenges of an era, asserting leadership at a time of national crisis, or articulating a large constitutional vision. The personal qualities and life experiences that a new Justice brings to the Court contain the seeds of the individual\u27s judicial service. Justice White, a skeptical but unflinching democrat, was no exception

The Solar-System-Scale Disk Around AB Aurigae

The young star AB Aurigae is surrounded by a complex combination of gas-rich and dust dominated structures. The inner disk which has not been studied previously at sufficient resolution and imaging dynamic range seems to contain very little gas inside a radius of least 130 astronomical units (AU) from the star. Using adaptive-optics coronagraphy and polarimetry we have imaged the dust in an annulus between 43 and 302 AU from the star, a region never seen before. An azimuthal gap in an annulus of dust at a radius of 102 AU, along with a clearing at closer radii inside this annulus, suggests the formation of at least one small body at an orbital distance of about 100 AU. This structure seems consistent with crude models of mean motion resonances, or accumulation of material at two of the Lagrange points relative to the putative object and the star. We also report a low significance detection of a point source in this outer annulus of dust. This source may be an overdensity in the disk due to dust accreting onto an unseen companion. An alternate interpretation suggests that the object's mass is between 5 and 37 times the mass of Jupiter. The results have implications for circumstellar disk dynamics and planet formation.Comment: 11 pages, 5 figures, accepted for publication in Astrophysical Journal, V. 680, June 10, 200

Natural History of the Porcine Bioprosthetic Heart Valve

The porcine bioprosthesis has been the prosthetic valve of choice at Henry Ford Hospital since October 1971. By 1979, 23 cases of degeneration had been seen, and the rate seven years after implantation was 16%. Now, with a ten-year follow-up, there are 41 degenerated valves. After seven years, the percent free of degeneration is 88%, (SE of 2% [standard error]); at eight years, 82% (SE of 2.9%,); at nine years, 80% (SE of 3.4%); and at ten years, the percent free of degeneration is 69% (SE of 6.5%,). There was no difference in degeneration between men and women, between aortic or mitral position, or between the valves which were or were not rinsed in antibiotics. The incidence of degeneration was significantly greater in patients under 35 years of age. Contrary to our expectations, the number of valves removed for degeneration has not increased linearly, although the number at risk has continued to rise. In 1977, we removed four valves for degeneration; in 1978, eight valves; in 1979, 77 valves; in 1980, five valves; and in 1981, ten valves. The duration of implantation for degenerated valves has increased from 56 months (SD [standard deviation] of 11 months) in 1977-78 to 77 months (SD of 19 months) in 1981. Analysis of cohorts from 1972,1973, 1974, all now followed for seven years, reveals that at seven years the percent free of degeneration for 1972 is 88% (SE of 4.4%,); for 1973, 83% (SE of 4.8%); and for 1974, 95% (SE of 2.6%). Although a difference is suggested, it is not yet statistically significant (p = .48) due to the small number of valves degenerating. The incidence of porcine bioprosthetic degeneration appears to be decreasing, possibly because valves manufactured later in the series are more durable

1987: Abilene Christian College Bible Lectures - Full Text

THE MIND OF CHRIST Being the Abilene Christian University Annual Bible Lectures 1987 Published by A.C.U. Press 1634 Campus Court Abilene, Texas 7960