1,013 research outputs found
Tentative Detection of the Nitrosylium Ion in Space
We report the tentative detection in space of the nitrosylium ion, NO.
The observations were performed towards the cold dense core Barnard 1-b. The
identification of the NO =2--1 line is supported by new laboratory
measurements of NO rotational lines up to the =8--7 transition
(953207.189\,MHz), which leads to an improved set of molecular constants: \,MHz, \,kHz, and \,MHz. The profile of the feature assigned to NO exhibits two
velocity components at 6.5 and 7.5 km s, with column densities of and cm, respectively. New
observations of NO and HNO, also reported here, allow to estimate the following
abundance ratios: (NO)/(NO), and
(HNO)/(NO). This latter value provides important constraints
on the formation and destruction processes of HNO. The chemistry of NO and
other related nitrogen-bearing species is investigated by the means of a
time-dependent gas phase model which includes an updated chemical network
according to recent experimental studies. The predicted abundance for NO
and NO is found to be consistent with the observations. However, that of HNO
relative to NO is too high. No satisfactory chemical paths have been found to
explain the observed low abundance of HNO. HSCN and HNCS are also reported here
with an abundance ratio of . Finally, we have searched for NNO,
NO, HNNO, and NNOH, but only upper limits have been obtained for
their column density, except for the latter for which we report a tentative
3- detection.Comment: To appear in the Astrophysical Journal October 20, 201
Iron Sharpens Iron: A Student’s Perspective on Diversity Outreach
POWER (Providing the Outside World with Empowerment and Resources), a student organization within the Texas Tech’s Collegiate Recovery Program established December 2015, elaborated on their members experience when engaging in the important effort of diversity outreach to persons in recovery from substance and alcohol use disorders and eating disorders. POWER describes their mission statement to provide a foundation and a voice for underrepresented individuals in recovery by delivering positive end results through opportunities for success with a vision to instill hope for a promising future. These members along with the director of the CCRC and another staff member shared what they have found to be most effective and ineffective when presenting to diverse groups in their community. The presenters provided educational and recovery resources used in reaching out but also the varying and tailored approaches and techniques utilized when conducting outreach work to specific marginalized populations. These materials and techniques have been honed through many presentations and experience since 2015. During their presentation, student leaders, and members of POWER, shared their own personal experiences of marginalization as well as their experience as presenters/peer leaders
Why Employees Do Bad Things: Moral Disengagement And Unethical Organizational Behavior
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90243/1/j.1744-6570.2011.01237.x.pd
Fabrication and performance of Nd1.95NiO4+δ (NNO) cathode supported microtubular solid oxide fuel cells
Trabajo presentado al 10th European Solid Oxide Fuell Cell Forum celebrado en Lucerna (Suiza) del 26 al 29 de Junio de 2012.Microtubular SOFC present significant advantages in comparison with the traditional planar SOFC configuration. In particular, the tubular design facilitates sealing and also reduces thermal gradients. As a consequence, rapid starts up times are possible. In addition, another advantage of the microtubular configuration is their higher power density per unit volume. Due to these properties, those devices are especially attractive for portable applications. There has been a great interest in microtubular SOFCs in the recent years, mainly using anode supported cells. Electrolyte supported cells have also been reported, but there are relatively few investigations using the cathode as the support. In the present paper, Nd1.95NiO4+δ (NNO) has been chosen as the cathode support, as it presents superior oxygen transport properties in comparison with other commonly used cathode materials, such as LSCF or LSM, and these material has been proven as an excellent cathode for SOFC and SOEC applications. Results on the fabrication and characterization of NNO cathode supported SOFC will be presented. The tubes were fabricated by cold isostatic pressing (CIP) using NNO powders and corn starch as the pore former. The electrolyte (GDC based) was deposited by wet powder spray (WPS) on top of the pre-sintered tubes and then co-sintered. Finally, a NiOGDC paste was dip-coated as the anode. Optimization of the fabrication process as well as the electrochemical performance of single cells will be further discussed.The authors thank grant MAT2009-14324-C02-01, financed by the Spanish Government (Ministerio de Ciencia e Innovación) and Feder program of the European Community, for funding the project. M.A.L.-B. thanks the JAE program (CSIC) for financial support.Peer Reviewe
Deuteration around the ultracompact HII region Mon R2
The massive star-forming region Mon R2 hosts the closest ultra-compact HII
region that can be spatially resolved with current single-dish telescopes. We
used the IRAM-30m telescope to carry out an unbiased spectral survey toward two
important positions (namely IF and MP2), in order to studying the chemistry of
deuterated molecules toward Mon R2. We found a rich chemistry of deuterated
species at both positions, with detections of C2D, DCN, DNC, DCO+, D2CO, HDCO,
NH2D, and N2D+ and their corresponding hydrogenated species and isotopologs.
Our high spectral resolution observations allowed us to resolve three velocity
components: the component at 10 km/s is detected at both positions and seems
associated with the layer most exposed to the UV radiation from IRS 1; the
component at 12 km/s is found toward the IF position and seems related to the
molecular gas; finally, a component at 8.5 km/s is only detected toward the MP2
position, most likely related to a low-UV irradiated PDR. We derived the column
density of all the species, and determined the deuterium fractions (Dfrac). The
values of Dfrac are around 0.01 for all the observed species, except for HCO+
and N2H+ which have values 10 times lower. The values found in Mon R2 are well
explained with pseudo-time-dependent gas-phase model in which deuteration
occurs mainly via ion-molecule reactions with H2D+, CH2D+ and C2HD+. Finally,
the [H13CN]/[HN13C] ratio is very high (~11) for the 10 km/s component, which
also agree with our model predictions for an age of ~0.01-0.1 Myr. The
deuterium chemistry is a good tool for studying star-forming regions. The
low-mass star-forming regions seem well characterized with Dfrac(N2H+) or
Dfrac(HCO+), but it is required a complete chemical modeling to date massive
star-forming regions, because the higher gas temperature together with the
rapid evolution of massive protostars.Comment: 14 pages of manuscript, 17 pages of apendix, 7 figures in the main
text, accepted for publication in A&
Kinematics of the ionized-to-neutral interfaces in Monoceros R2
Context. Monoceros R2 (Mon R2), at a distance of 830 pc, is the only
ultra-compact H ii region (UC H ii) where its associated photon-dominated
region (PDR) can be resolved with the Herschel Space Observatory. Aims. Our aim
is to investigate observationally the kinematical patterns in the interface
regions (i.e., the transition from atomic to molecular gas) associated with Mon
R2. Methods. We used the HIFI instrument onboard Herschel to observe the line
profiles of the reactive ions CH+, OH+ and H2O+ toward different positions in
Mon R2. We derive the column density of these molecules and compare them with
gas-phase chemistry models. Results. The reactive ion CH+ is detected both in
emission (at central and red-shifted velocities) and in absorption (at
blue-shifted velocities). OH+ is detected in absorption at both blue- and
red-shifted velocities, with similar column densities. H2O+ is not detected at
any of the positions, down to a rms of 40 mK toward the molecular peak. At this
position, we find that the OH+ absorption originates in a mainly atomic medium,
and therefore is associated with the most exposed layers of the PDR. These
results are consistent with the predictions from photo-chemical models. The
line profiles are consistent with the atomic gas being entrained in the ionized
gas flow along the walls of the cavity of the H ii region. Based on this
evidence, we are able to propose a new geometrical model for this region.
Conclusions. The kinematical patterns of the OH+ and CH+ absorption indicate
the existence of a layer of mainly atomic gas for which we have derived, for
the first time, some physical parameters and its dynamics.Comment: 6 pages, 5 figures. Accepted for publication in A&
Spatial distribution of small hydrocarbons in the neighborhood of the Ultra Compact HII region Monoceros R2
We study the chemistry of small hydrocarbons in the photon-dominated regions
(PDRs) associated with the ultra-compact HII region Mon R2. Our goal is to
determine the variations of the abundance of small hydrocarbons in a high-UV
irradiated PDR and investigate their chemistry. We present an observational
study of CH, CCH and c-CH in Mon R2 combining data obtained with the
IRAM 30m telescope and Herschel. We determine the column densities of these
species, and compare their spatial distributions with that of polycyclic
aromatic hydrocarbon (PAH). We compare the observational results with different
chemical models to explore the relative importance of gas-phase, grain-surface
and time-dependent chemistry in these environments. The emission of the small
hydrocarbons show different patterns. The CCH emission is extended while CH and
c-CH are concentrated towards the more illuminated layers of the PDR.
The ratio of the column densities of c-CH and CCH shows spatial
variations up to a factor of a few, increasing from
_3_2 in the envelope to a maximum of
towards the 8m emission peak. Comparing these results
with other galactic PDRs, we find that the abundance of CCH is quite constant
over a wide range of G, whereas the abundance of c-CH is higher in
low-UV PDRs. In Mon R2, the gas-phase steady-state chemistry can account
relatively well for the abundances of CH and CCH in the most exposed layers of
the PDR, but falls short by a factor of 10 to reproduce c-CH.
In the molecular envelope, time-dependent effects and grain surface chemistry
play a dominant role in determining the hydrocarbons abundances. Our study
shows that CCH and c-CH present a complex chemistry in which UV
photons, grain-surface chemistry and time dependent effects contribute to
determine their abundances.Comment: 18 pages, 11 figures, 7 tables. Proposed for acceptance in A&A.
Abstract abridge
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