Understanding how place matters for kids

Community development

Sceloporus slevini

Number of Pages: 6Integrative BiologyGeological Science

Nanoscale Manipulation of Surfaces and Interfaces: Engineering Electrical Properties Through Nanofabrication

Nanotechnology interest and research has increased dramatically over the last decade, but there remain fundamental limitations and barriers to the fabrication of ever smaller devices. To overcome these limitations, new nanofabrication methods and novel nanoscale systems must be explored. To form nanoscale systems, we must have the ability to electrically interconnect various nanoscale parts. To do that, methods must be developed to form nanowires and nanofeatures in a very controlled fashion with arbitrary shapes. It should be noted, however, that materials' properties can change at nanoscale sizes, so these nanowires and nanofeatures themselves must be studied to ensure they function as designed. Materials with unique electronic properties and low dimensionalities, like graphene and carbon nanotubes also need to be studied for potential use in nanoscale devices. Graphene has been found to be electronically tunable by doping, causing it to be able to function as a semiconductor or as a metallic conductor. Understanding this doping interaction will help in the design and implementation of novel nanoscale systems and devices. The first part of this work puts forth a method for fabricating metallic nanofeatures into self-assembled monolayer resists. An atomic force microscope (AFM) is used with methods called nanoetching and grafting and oxidative lithography to form patterned nanofeatures down to 20 nm in width. Nanoetching and grafting involve using the AFM tip to directly remove molecules and replace them with new ones, creating a nanopattern. Oxidative lithography uses a conductive AFM tip as a tiny electrode to write nanopatterns into surfaces by very localized electrochemical oxidation. These nanopatterns are then exposed to an electroless copper plating solution, which selectively plates copper right onto those nanopatterns, to form copper nanofeatures. These are characterized with the AFM that helped form them. With this AFM based method, features of any shape can potentially be formed, providing a way to wire up more complex nanodevices and circuitry. The second part investigates the interaction between graphene-like materials and adsorbates. These interactions are becoming increasingly important as these materials become incorporated into more devices. There has been much study recently focused on graphene and graphene-like materials, such as carbon nanotubes and graphite. Graphene is of particular interest because of its low dimensionality, being a two-dimensional sheet of sp2 hybridized carbon atoms, and its unique properties. It is tough and flexible, but what is most interesting is that its electronic properties are very tunable. Adsorbates can dope it p-type or n-type, so it behaves more like a semiconductor or a metal, respectively. In this work, azulene derivatives and gold nanoparticles are studied as potential adsorbates on graphene-like materials. Azulene molecules themselves have very tunable HOMO and LUMO levels, and it could be possible to dope graphite-like materials in different fashions with different types of azulenes. Gold nanoparticles can also be tunable with size and shape, and their ability to dope graphene-like materials is of interest. Using an AFM technique called surface potential mapping, the electrostatic potential of azulenes adsorbed onto graphite was studied. It was found that azulene and azulene compounds with electron withdrawing groups at the 1 and 3 positions were more negative in the potential than the graphite, indicating they were pulling electrons out of the material. An azulene compound with electron donating groups at the 1 and 3 positions was positive in potential with respect to the graphite surface, indicating donation of electrons to the graphite. This is good evidence that azulenes can be tunable dopants for modifying the properties of graphene-like materials. Using AFM based techniques, this work advances methods to form and electrically characterize nanoscale metallic features and decorated graphene-like materials that could have important applications as nanotechnology moves forward into complex nanodevice fabrication. It also gives insight into a novel system, azulenes on a graphene-like material, at a nanoscale level of resolution. Study of nanosystems like these is integral to the advancement of nanotechnology as a whole

Method in Catholic Bioethics: ANH and PVS Patients

This paper discusses the methods used in Catholic Social Teaching (CST), a part of the Catholic Moral Tradition (CMT), as applied to bioethical problem solving and decision-making. In order to apply CST to a concrete bioethical problem and to analyze the methods used in CST, the nature and extent of the obligation to provide artificial nutrition and hydration (ANH) to patients in a persistent vegetative state (PVS) is addressed. In particular, this paper focuses upon the extent to which providing ANH to PVS patients is or should be considered morally obligatory. In this discussion, the current official view of the Roman Catholic Church (Church) is reviewed, as evidenced for the United States by the changes made in 2009 to Directive 58 of the Ethical and Religious Directives for Catholic Health Care Services (ERD), as well as contrary viewpoints. This paper argues that the methodology of CST, which includes the balancing of benefits and burdens, is a practical and ethical way to resolve difficult bioethical cases, including those where care decisions need to be made for patients in a PVS, defending against concerns that have been raised by some in or speaking for the Church about the withdrawal of ANH from PVS patients

Double-Peaked Narrow-Line Active Galactic Nuclei. II. The Case Of Equal Peaks

Active galactic nuclei (AGNs) with double-peaked narrow lines (DPAGNs) may be caused by kiloparsec-scale binary AGNs, bipolar outflows, or rotating gaseous disks. We examine the class of DPAGNs in which the two narrow-line components have closely similar intensity as being especially likely to involve disks or jets. Two spectroscopic indicators support this likelihood. For DPAGNs from Smith et al., the "equal-peaked" objects (EPAGNs) have [Ne V]/[O III] ratios lower than for a control sample of non-double-peaked AGNs. This is unexpected for a pair of normal AGNs in a galactic merger, but may be consistent with [O III] emission from a rotating ring with relatively little gas at small radii. Also, [O III]/H beta ratios of the redshifted and blueshifted systems in the EPAGN are more similar to each other than in a control sample, suggestive of a single ionizing source and inconsistent with the binary interpretation.University Cooperative Society of the University of Texas at AustinJane and Roland Blumberg Cenntenial Professorship in AstronomyAlfred P. Sloan FoundationNational Aeronautics and Space AdministrationNational Science FoundationU.S. Department of EnergyJapanese MonbukagakushoMax Planck SocietyUniversity of ChicagoInstitute for Advanced StudyJapan Participation GroupJohns Hopkins UniversityKorean Scientist GroupLos Alamos National LaboratoryMax-Planck-Institute for Astronomy (MPIA)Max-Planck-Institute for Astrophysics (MPA)New Mexico State UniversityUniversity of PittsburghUniversity of PortsmouthPrinceton UniversityUnited States Naval ObservatoryUniversity of WashingtonFermilabAstronom

The Jet-Driven Outflow In The Radio Galaxy SDSS J1517+3353: Implications For Double-Peaked Narrow-Line Active Galactic Nucleus

We report on the study of an intriguing active galaxy that was selected as a potential multiple supermassive black hole merger in the early-type host SDSS J151709.20+335324.7 (z = 0.135) from a complete search for double-peaked [O III] lines from the SDSS spectroscopic quasi-stellar object (QSO) database. Ground-based SDSS imaging reveals two blue structures on either side of the photometric center of the host galaxy, separated from each other by about 5.7 kpc. From a combination of SDSS fiber and Keck/HIRES long-slit spectroscopy, it is demonstrated that, in addition to these two features, a third distinct structure surrounds the nucleus of the host galaxy. All three structures exhibit highly ionized line emission with line ratios characteristic of Seyfert II active galactic nuclei. The analysis of spatially resolved emission-line profiles from the HIRES spectrum reveal three distinct kinematic subcomponents, one at rest and the other two moving at -350 km s(-1) and 500 km s(-1) with respect to the systemic velocity of the host galaxy. A comparison of imaging and spectral data confirm a strong association between the kinematic components and the spatial knots, which implies a highly disturbed and complex active region in this object. A comparative analysis of the broadband positions, colors, kinematics, and spectral properties of the knots in this system lead to two plausible explanations: (1) a multiple active galactic nucleus (AGN) produced due to a massive dry merger, or (2) a very powerful radio jet-driven outflow. Subsequent VLA radio imaging reveals a clear jet aligned with the emission-line gas, confirming the latter explanation. We use the broadband radio measurements to examine the impact of the jet on the interstellar medium of the host galaxy, and find that the energy in the radio lobes can heat a significant fraction of the gas to the virial temperature. Finally, we discuss tests that may help future surveys distinguish between jet-driven kinematics and true black-hole binaries. J1517+3353 is a remarkable laboratory for AGN feedback and warrants deeper follow-up study. In the Appendix, we present high-resolution radio imaging of a second AGN with double-peaked [O III] lines, SDSS J112939.78+605742.6, which shows a sub-arcsecond radio jet. If the double-peaked nature of the narrow lines in radio-loud AGNs are generally due to radio jet interactions, we suggest that extended radio structure should be expected in most of such systems.NSF AST-0507483, AST-0808133University of Texas at AustinAlfred P. Sloan FoundationParticipating InstitutionsNational Aeronautics and Space AdministrationU.S. Department of EnergyJapanese MonbukagakushoMax Planck SocietyAstronom