5,902 research outputs found
Conductivity of Mono- and Divalent Cations in the Microporous Zincosilicate VPI-9
Impedance spectroscopy is used to investigate the long-range ionic conductivity of the microporous, zincosilicate VPI-9 (Si/Zn = 4.0) (International Zeolite Association framework type VNI) containing the alkali cations Li^+, Na^+, K^+, Rb^+, and Cs^+, and the alkaline earth cations Mg^(2+), Ca^(2+), and Sr^(2+). Monovalent cation-exchanged samples Li- and Na-VPI-9 lose X-ray crystallinity upon vacuum dehydration at 450 °C, whereas K-, Rb-, and Cs-VPI-9 remain crystalline and exhibit conductivities of 1.7 × 10^(−4), 3.5 × 10^(−4), and 4.9 × 10^(−4) S/cm, respectively, at 450 °C and activation energies of 0.72, 0.64, and 0.69 eV, respectively, in the temperature range 150−450 °C. Divalent cation-exchanged sample Mg-VPI-9 also loses X-ray crystallinity, but Ca- and Sr-VPI-9 remain crystalline and exhibit conductivities of 2.3 × 10^(−6) S/cm and 7.7 × 10^(−7) S/cm, respectively, at 450 °C, and activation energies of 0.88 and 0.91 eV, respectively, over the temperature range 150−450 °C. When compared to aluminosilicate zeolite X (Si/Al = 1.25) exchanged with the same cations, all crystalline M-VPI-9 materials have greater conductivities than M-X, with the exception of K-X (1.6 × 10^(−3) S/cm at 450 °C), with the greatest differences arising between the divalent exchanged materials. Dense, crystalline zincosilicate samples with the compositions K_2ZnSi_xO_(2(x+1)) (x = 2−5), Rb_2ZnSi_5O_(12), and Cs_2ZnSi_5O_(12) are also prepared and characterized for comparison with the microporous materials and exhibit much lower conductivities than their microporous counterparts at the same composition
Cosmic Strings, Zero Modes and SUSY breaking in Nonabelian N=1 Gauge Theories
We investigate the microphysics of cosmic strings in Nonabelian gauge
theories with N=1 supersymmetry. We give the vortex solutions in a specific
example and demonstrate that fermionic superconductivity arises because of the
couplings and interactions dictated by supersymmetry. We then use supersymmetry
transformations to obtain the relevant fermionic zero modes and investigate the
role of soft supersymmetry breaking on the existence and properties of the
superconducting strings.Comment: 12 pages, RevTex, submitted to Phys. Rev.
Ground/Flight Correlation of Aerodynamic Loads with Structural Response
Ground and flight tests provide a basis and methodology for in-flight characterization of the aerodynamic and structural performance through the monitoring of the fluid-structure interaction. The NF-15B flight tests of the Intelligent Flight Control System program provided a unique opportunity to test the correlation of aerodynamic loads with points of flow attaching and detaching from the surface, which are also known as flow bifurcation points, as observed in a previous wind tunnel test performed at the U.S. Air Force Academy (Colorado Springs, Colorado). Moreover, flight tests, along with the subsequent unsteady aerodynamic tests in the NASA Transonic Dynamics Tunnel (TDT), provide a basis using surface flow sensors as means of assessing the aeroelastic performance of flight vehicles. For the flight tests, the NF-15B tail was instrumented with hot-film sensors and strain gages for measuring root-bending strains. This data were gathered via selected sideslip maneuvers performed at level flight and subsonic speeds. The aerodynamic loads generated by the sideslip maneuver resulted in a structural response, which were then compared with the hot-film sensor signals. The hot-film sensor signals near the stagnation region were found to be highly correlated with the root-bending strains. For the TDT tests, a flexible wing section developed under the U.S. Air Force Research Lab SensorCraft program was instrumented with strain gages, accelerometers, and hot-film sensors at two span stations. The TDT tests confirmed the correlation between flow bifurcation points and the wing structural response to tunnel-generated gusts. Furthermore, as the wings structural modes were excited by the gusts, a gradual phase change between the flow bifurcation point and the structural mode occurred during a resonant condition
Microwave-assisted synthesis of a MK2 inhibitor by Suzuki-Miyaura coupling for study in Werner syndrome cells
Microwave-assisted Suzuki-Miyaura cross-coupling reactions have been employed towards the synthesis of three different MAPKAPK2 (MK2) inhibitors to study accelerated aging in Werner syndrome (WS) cells, including the cross-coupling of a 2-chloroquinoline with a 3-pyridinylboronic acid, the coupling of an aryl bromide with an indolylboronic acid and the reaction of a 3-amino-4-bromopyrazole with 4-carbamoylphenylboronic acid. In all of these processes, the Suzuki-Miyaura reaction was fast and relatively efficient using a palladium catalyst under microwave irradiation. The process was incorporated into a rapid 3-step microwave-assisted method for the synthesis of a MK2 inhibitor involving 3-aminopyrazole formation, pyrazole C-4 bromination using N-bromosuccinimide (NBS), and Suzuki-Miyaura cross-coupling of the pyrazolyl bromide with 4-carbamoylphenylboronic acid to give the target 4-arylpyrazole in 35% overall yield, suitable for study in WS cells
Particularity, potentiation, citizenship and pragmatism
The case studies presented in this volume have addressed HIV technologies as formations
of the material, embodied, social and political in modes of engagement with the HIV
epidemic. As argued throughout, this notion of HIV technologies is needed to grapple
with the particularities of the HIV pandemic in the treatment possibility era. This
approach provides a way of conceptualising HIV medical, social, cultural and political
treatment and prevention technologies and their hybrids. The perspective draws attention to the sociocultural and political aspects of HIV medical treatment technologies and to the increasingly bio-technical bases for HIV prevention. It also encourages reflection on forms of HIV prevention and social care that are not typically understood as technologies
but that, as has been demonstrated, share many structural and political features with
technical, biomedical means of addressing HIV. This perspective can also allow us to
grapple with relations between treatment and prevention, as many of the chapters in this
volume have demonstrated
HIV Technologies
Here, we address the governance of the HIV and AIDS pandemic with reference to the social aspects of technology in international contexts. The term
'technology' is used to encompass medical technologies such as HIV treatment, but
also other ‘technologies’ of health care, including psychosocial and social
interventions and communications media applied to moderating HIV's impact and to
preventing HIV transmission. HIV technologies of the biomedical kind have become a focus in the research and policy literature. Policy frameworks advocate for close attention to the relationship between HIV treatment and prevention (Global HIV
Prevention Working Group, 2008: 6)(see also Mykhalovskiy, this volume) and an
address to ‘psychosocial’ factors (UNAIDS, 2009b), as well as integration between
HIV and other health and social policy initiatives, around for instance TB, drug use, and gender-based violence (UNAIDS, 2009a). Researchers have warned of the need to consider the social and cultural dimensions of biomedical interventions (Peltzer et al., 2007) such as male circumcision. We contribute to these debates by investigating the social and cultural dimensions of HIV technologies that find
expression in different parts of the world.
While there has been much written about the HIV pandemic, recent social scientific
research is largely directed at description and policy improvement. For some time now
we have lacked a sustained social science engagement with the pandemic that
addresses the changing technologies of its governance. We also lack texts that
consider HIV technologies globally. From time to time, inspiring research does
appear in the literature, some of it produced by the contributors to this collection. However, we argue that there is still a need to bring together, and reflect on, theoretically informed, innovative research from different parts of the world
concerning the current circumstances of the HIV/AIDS pandemic
CMB power spectrum contribution from cosmic strings using field-evolution simulations of the Abelian Higgs model
We present the first field-theoretic calculations of the contribution made by
cosmic strings to the temperature power spectrum of the cosmic microwave
background (CMB). Unlike previous work, in which strings were modeled as
idealized one-dimensional objects, we evolve the simplest example of an
underlying field theory containing local U(1) strings, the Abelian Higgs model.
Limitations imposed by finite computational volumes are overcome using the
scaling property of string networks and a further extrapolation related to the
lessening of the string width in comoving coordinates. The strings and their
decay products, which are automatically included in the field theory approach,
source metric perturbations via their energy-momentum tensor, the unequal-time
correlation functions of which are used as input into the CMB calculation
phase. These calculations involve the use of a modified version of CMBEASY,
with results provided over the full range of relevant scales. We find that the
string tension required to normalize to the WMAP 3-year data at multipole
is , where we have quoted statistical and systematic errors
separately, and is Newton's constant. This is a factor 2-3 higher than
values in current circulation.Comment: 23 pages, 14 figures; further optimized figures for 1Mb size limit,
appendix added before submission to journal, matches accepted versio
The effect of RO3201195 and a pyrazolyl ketone P38 MAPK inhibitor library on the proliferation of Werner syndrome cells
No description supplie
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