Fe/Co Alloys for the Catalytic Chemical Vapor Deposition Synthesis of Single- and Double-Walled Carbon Nanotubes (CNTs). 2. The CNT−Fe/Co−MgAl2O4 System

A detailed 57Fe Mössbauer study of the Mg(0.8)Fe(0.2-y)Co(y)Al2O4 (y = 0, 0.05, 0.1, 0.15, 0.2) solid solutions and of the CNT-Fe/Co-MgAl2O4 nanocomposite powders prepared by reduction in H2-CH4 has allowed characterization of the different iron phases involved in the catalytic process of carbon nanotube (CNT) formation and to correlate these results with the carbon and CNT contents. The oxide precursors consist of defective spinels of general formulas (Mg(1-x-y)(2+)Fe(x-3alpha)(2+)Fe(2alpha)(3+)[symbol: see text](alpha)Co(y)(2+)Al2(3+))O4(2-) . The metallic phase in the CNT-Fe/Co-MgAl2O4 nanocomposite powders is mostly in the form of the ferromagnetic alpha-Fe/Co alloy with the desired composition. For high iron initial proportions, the additional formation of Fe3C and gamma-Fe-C is observed while for high cobalt initial proportions, the additional formation of a gamma-Fe/Co-C phase is favored. The higher yield of CNTs is observed for postreaction alpha-Fe(0.50)Co(0.50) catalytic particles, which form no carbide and have a narrow size distribution. Alloying is beneficial for this system with respect to the formation of CNTs

Mapping Hydrogen in the Galaxy, Galactic Halo, and Local Group with ALFA: The GALFA-HI Survey Starting with TOGS

Radio observations of gas in the Milky Way and Local Group are vital for understanding how galaxies function as systems. The unique sensitivity of Arecibo's 305m dish, coupled with the 7-beam Arecibo L-Band Feed Array (ALFA), provides an unparalleled tool for investigating the full range of interstellar phenomena traced by the HI 21cm line. The GALFA (Galactic ALFA) HI Survey is mapping the entire Arecibo sky over a velocity range of -700 to +700 km/s with 0.2 km/s velocity channels and an angular resolution of 3.4 arcminutes. We present highlights from the TOGS (Turn on GALFA Survey) portion of GALFA-HI, which is covering thousands of square degrees in commensal drift scan observations with the ALFALFA and AGES extragalactic ALFA surveys. This work is supported in part by the National Astronomy and Ionosphere Center, operated by Cornell University under cooperative agreement with the National Science Foundation.Comment: 3 pages, including 2 figure pages; figure image quality significantly reduced; for full resolution version, please see http://www.naic.edu/~gibson/cv/ao08_writeup.pdf ; to be published in AIP conference proceedings for ``The Evolution of Galaxies through the Neutral Hydrogen Window'', eds. R. Minchin & E. Momjia

"GiGa": the Billion Galaxy HI Survey -- Tracing Galaxy Assembly from Reionization to the Present

In this paper, we review the Billion Galaxy Survey that will be carried out at radio--optical wavelengths to micro--nanoJansky levels with the telescopes of the next decades. These are the Low-Frequency Array, the Square Kilometer Array and the Large Synoptic Survey Telescope as survey telescopes, and the Thirty Meter class Telescopes for high spectral resolution+AO, and the James Webb Space Telescope (JWST) for high spatial resolution near--mid IR follow-up. With these facilities, we will be addressing fundamental questions like how galaxies assemble with super-massive black-holes inside from the epoch of First Light until the present, how these objects started and finished the reionization of the universe, and how the processes of star-formation, stellar evolution, and metal enrichment of the IGM proceeded over cosmic time. We also summarize the high-resolution science that has been done thus far on high redshift galaxies with the Hubble Space Telescope (HST). Faint galaxies have steadily decreasing sizes at fainter fluxes and higher redshifts, reflecting the hierarchical formation of galaxies over cosmic time. HST has imaged this process in great structural detail to z<~6. We show that ultradeep radio-optical surveys may slowly approach the natural confusion limit, where objects start to unavoidably overlap because of their own sizes, which only SKA can remedy with HI redshifts for individual sub-clumps. Finally, we summarize how the 6.5 meter James Webb Space Telescope (JWST) will measure first light, reionization, and galaxy assembly in the near--mid-IR.Comment: 8 pages, LaTeX2e requires 'aip' style (included), 8 postscript figures. To appear in the proceedings of the `The Evolution of Galaxies through the Neutral Hydrogen Window' conference, Arecibo Observatory Feb 1-3, 2008; Eds. R. Minchin & E. Momjian, AIP Conf Pro

The HI distribution in the outskirts of M33 with the ALFALFA survey

Spiral galaxies appear to be dynamical systems whose disks are still forming at the current epoch and which continue to accrete mass. The presence of extraplanar gas in spirals indicates that galactic halos can contain at least part of the material needed to fuel the star formation activity in their disks. Here we present the analysis of the ALFALFA survey data in the region of M33 aimed at searching high velocity clouds around this Local Group galaxy. We find a varied population of HI clouds with masses ranging between 4 x 10^4 and few times 10^6 M_sun. We also detect an extended HI complex at anomalous velocities, whose extragalactic nature cannot be firmly established. We estimate that the total amount of neutral hydrogen mass associated to these clouds is around 10^7 M_sun.Comment: 3 pages, 2 figures, to appear in the Conference Proceedings "The Evolution of Galaxies through the Neutral Hydrogen Window",eds. R. Minchin & E. Momjia

Regulation of the SCOLE configuration

Studies were performed to determine location for proof mass actuators, if a significant reduction in the number of sensors would work, and to design a control law to meet requirements for line of sight error and actuators. Conclusions are drawn and briefly discussed

Simple tandem repeat (TTTA)(n )polymorphism in CYP19 (aromatase) gene and breast cancer risk in Nigerian women

BACKGROUND: Breast cancer is the most common cancer and the leading cause of cancer related deaths in women worldwide. The incidence of the disease is increasing globally and this increase is occurring at a faster rate in population groups that hirtherto enjoyed low incidence. This study was designed to evaluate the role of a simple tandem repeat polymorphism (STRP) in the aromatase (CYP19) gene in breast cancer susceptibility in Nigerian women, a population of indigenous sub-Saharan African ancestry. METHODS: A case-control study recruiting 250 women with breast cancer and 250 women without the disease from four University Teaching Hospitals in Southern Nigeria was carried out between September 2002 and April 2004. Participants were recruited from the surgical outpatient clinics and surgical wards of the Nigerian institutions. A polymerase chain reaction (PCR)-based assay was employed for genotyping and product sizes were detected with an ABI 3730 DNA Analyzer. RESULTS: Conditional logistic regression analysis revealed that harboring the putative high risk genotypes conferred a 29% increased risk of breast cancer when all women in the study were considered (Odds ratio [OR] = 1.29, 95% confidence interval [CI] 0.83–2.00), although this association was not statistically significant. Subgroup analysis based on menopausal status showed similar results among premenopausal women (OR = 1.35, 95% CI 0.76–2.41 and postmenopausal women (OR = 1.27, 95% CI 0.64–2.49). The data also demonstrated marked differences in the distribution of (TTTA)(n )repeats in Nigerian women compared with other populations. CONCLUSION: This study has shown that harboring 10 or more repeats of the microsatellite (TTTA)(n )repeats of the CYY19 gene is associated with a modest increased risk of breast cancer in Nigerian women

Mössbauer spectroscopy study of MgAl2O4-matrix nanocomposite powders containing carbon nanotubes and iron-based nanoparticles

Materials involved in the catalytic formation of carbon nanotubes are for the first time systematically studied by Mössbauer spectroscopy between 11 K and room temperature. Mg1−xFexAl2O4 (x=0.1, 0.2, 0.3, 0.4) solid solutions are transformed into carbon nanotubes–Fe/Fe3C–MgAl2O4 composite powders by reduction in a H2–CH4 gas mixture. The oxides are defective spinels of general formulae (Mg1−x2+Fex−3α2+Fe2α3+□αAl23+)O42−. Ferromagnetic α-Fe, ferromagnetic Fe3C and a γ-Fe form, the latter possibly corresponding to a γ-Fe–C alloy, are detected in the composite powders. An attempt is made to correlate these results with the microstructure of the powder. It seems that the nanoparticles, which catalyze the formation of the carbon nanotubes, are detected as Fe3C in the post-reaction Mössbauer spectroscopy analysis

Decreased soluble guanylate cyclase contributes to cardiac dysfunction induced by chronic doxorubicin treatment in mice

Aims: The use of doxorubicin, a potent chemotherapeutic agent, is limited by cardiotoxicity. We tested the hypothesis that decreased soluble guanylate cyclase (sGC) enzyme activity contributes to the development of doxorubicin-induced cardiotoxicity. Results: Doxorubicin administration (20 mg/kg, intraperitoneally [IP]) reduced cardiac sGC activity in wild-type (WT) mice. To investigate whether decreased sGC activity contributes to doxorubicin-induced cardiotoxicity, we studied mice with cardiomyocyte-specific deficiency of the sGC alpha 1-subunit (mice with cardiomyocyte-specific deletion of exon 6 of the sGC alpha 1 allele [sGC alpha 1(-/-CM)]). After 12 weeks of doxorubicin administration (2 mg/kg/week IP), left ventricular (LV) systolic dysfunction was greater in sGC alpha 1(-/-CM) than WT mice. To further assess whether reduced sGC activity plays a pathogenic role in doxorubicin-induced cardiotoxicity, we studied a mouse model in which decreased cardiac sGC activity was induced by cardiomyocyte-specific expression of a dominant negative sGC alpha 1 mutant (DNsGC alpha 1) upon doxycycline removal (Tet-off). After 8 weeks of doxorubicin administration, DNsGC alpha 1(tg/+), but not WT, mice displayed LV systolic dysfunction and dilatation. The difference in cardiac function and remodeling between DNsGC alpha 1(tg/+) and WT mice was even more pronounced after 12 weeks of treatment. Further impairment of cardiac function was attenuated when DNsGC alpha 1 gene expression was inhibited (beginning at 8 weeks of doxorubicin treatment) by administering doxycycline. Furthermore, doxorubicin-associated reactive oxygen species generation was higher in sGC alpha 1-deficient than WT hearts. Innovation and Conclusion: These data demonstrate that a reduction in cardiac sGC activity worsens doxorubicin-induced cardiotoxicity in mice and identify sGC as a potential therapeutic target. Various pharmacological sGC agonists are in clinical development or use and may represent a promising approach to limit doxorubicin-associated cardiotoxicity

Cardiovascular and pharmacological implications of haem-deficient NO-unresponsive soluble guanylate cyclase knock-in mice

Oxidative stress, a central mediator of cardiovascular disease, results in loss of the prosthetic haem group of soluble guanylate cyclase (sGC), preventing its activation by nitric oxide (NO). Here we introduce Apo-sGC mice expressing haem-free sGC. Apo-sGC mice are viable and develop hypertension. The haemodynamic effects of NO are abolished, but those of the sGC activator cinaciguat are enhanced in apo-sGC mice, suggesting that the effects of NO on smooth muscle relaxation, blood pressure regulation and inhibition of platelet aggregation require sGC activation by NO. Tumour necrosis factor (TNF)-induced hypotension and mortality are preserved in apo-sGC mice, indicating that pathways other than sGC signalling mediate the cardiovascular collapse in shock. Apo-sGC mice allow for differentiation between sGC-dependent and -independent NO effects and between haem-dependent and -independent sGC effects. Apo-sGC mice represent a unique experimental platform to study the in vivo consequences of sGC oxidation and the therapeutic potential of sGC activators