198 research outputs found
Electrodeposition of CuâNi Composite Coatings
The electrodeposition of CuâNi incorporated with nano- to microparticles to produce metal matrix composites has been reviewed in this chapter. The inclusion of particles into the metal matrix produced enhanced properties in the areas of electronics, mechanics, electrochemistry, and corrosion. In electronics, an increase in the magnetic properties and durability for microactuators was observed. Measurements of the mechanical properties showed an increase in hardness, wear resistance, shear adhesion, and tensile strength for the material. The corrosion resistance of the metal matrix coatings was improved over that of pure CuâNi. As the accessibility of nanoparticles continues to increase, the interest in reduced cost and low-temperature electrodeposited metal matrix composites continues to rise. However, only a small number of articles have investigated CuâNi composite coatings; these composite coatings need further examination due to their advantageous properties
Simvastatin suppresses experimental aortic aneurysm expansion
ObjectiveAbdominal aortic aneurysm (AAA) formation is a result of inflammation and extracellular matrix (ECM) remodeling mediated by matrix metalloproteinases (MMPs). Hydroxymethylglutaryl-coenzyme A inhibitors (statins), although clinically used as lipid-lowering agents, have also been demonstrated to have anti-inflammatory effects. This study was designed to determine whether the hydroxymethylglutaryl-coenzyme A inhibitor simvastatin suppresses aneurysm formation in an elastase-induced rat AAA model.MethodsAneurysms were created in adult male Wistar rats by infusion of elastase into isolated infrarenal aortic segments. The rats were randomized to receive either simvastatin (n = 17) or placebo (n = 17) by gastric lavage daily starting the day before surgery. The rats were euthanized and the infrarenal aortas harvested on postoperative day 7. Aortic diameters were measured before infusion, immediately after infusion, and at the time of harvesting. Protein expression was measured by immunoblot analysis. Gene expression profiling using Affymetrix U34A rat genome chips was performed to identify changes in gene expression caused by simvastatin treatment.ResultsMean aneurysm diameter was significantly less in the simvastatin treatment group compared with controls (3.4 ± 0.08 mm vs 4.3 ± 0.19 mm; P = .0001). MMP-9 and nuclear factor-ÎșB protein levels were decreased in the aortas of simvastatin-treated animals. Gene microarray analysis revealed 315 genes with statistically significant changes in expression (P < .05) in the simvastatin group. Genes related to inflammation, ECM remodeling, and oxidative stress function were downregulated. These included genes for interleukin 1, interleukin 4, inducible nitric oxide synthase, P-selectin, platelet-derived growth factor α, tumor necrosis factor, and several chemokines.ConclusionsSimvastatin significantly suppresses experimental aneurysm expansion and reduces protein levels of MMP-9 and nuclear factor-ÎșB. Gene array analysis provides evidence that several mediators of inflammation, matrix remodeling, and oxidative stress are downregulated by simvastatin treatment. This suggests that simvastatin inhibits AAA formation by blocking the expression of certain proinflammatory genes. Simvastatin may be useful as an adjuvant therapy to suppress the growth of small aneurysms.Clinical RelevanceHuman aortic aneurysms are characterized histologically by an inflammatory infiltrate with severe proteolytic destruction. Statins, although used clinically as lipid-lowering agents, have been shown to have anti-inflammatory effects. Simvastatin reduced experimental aneurysm size in this study. It seems that this reduction is mediated by interfering with multiple pathways, including oxidative stress, inflammation, and ECM and matrix remodeling. Further study into the effect of statins in reducing the growth of AAAs in patients is warranted
Parties, promiscuity and politicisation: business-political networks in Poland
Research on post-communist political economy has begun to focus on the interface between business and politics. It is widely agreed that informal networks rather than business associations dominate this interface, but there has been very little systematic research in this area. The literature tends to assume that a politicised economy entails business-political networks that are structured by parties. Theoretically, this article distinguishes politicisation from party politicisation and argues that the two are unlikely to be found together in a post-communist context. Empirically, elite survey data and qualitative interviews are used to explore networks of businesspeople and politicians in Poland. Substantial evidence is found against the popular idea that Polish politicians have business clienteles clearly separated from each other according to party loyalties. Instead, it is argued that these politicians and businesspeople are promiscuous. Since there seems to be little that is unusual about the Polish case, this conclusion has theoretical, methodological, substantive and policy implications for other post-communist countries
Cost Containment Through Disability Prevention: Preliminary Results of a Health Promotion Workshop for People with Physical Disabilities
The Disability Prevention Project at the University of Montana and the University of Kansas has developed and evaluated an eight week workshop and self-help manual that targets the prevention and management of secondary conditions among adults with spinal cord injuries. The preliminary results of this intervention are very encouraging
Balloon Measurements of Cosmic Ray Muon Spectra in the Atmosphere along with those of Primary Protons and Helium Nuclei over Mid-Latitude
We report here the measurements of the energy spectra of atmospheric muons
and of the cosmic ray primary proton and helium nuclei in a single experiment.
These were carried out using the MASS superconducting spectrometer in a balloon
flight experiment in 1991. The relevance of these results to the atmospheric
neutrino anomaly is emphasized. In particular, this approach allows
uncertainties caused by the level of solar modulation, the geomagnetic cut-off
of the primaries and possible experimental systematics to be decoupled in the
comparison of calculated fluxes of muons to measured muon fluxes. The muon
observations cover the momentum and depth ranges of 0.3-40 GeV/c and 5-886
g/cmsquared, respectively. The proton and helium primary measurements cover the
rigidity range from 3 to 100 GV, in which both the solar modulation and the
geomagnetic cut-off affect the energy spectra at low energies.Comment: 31 pages, including 17 figures, simplified apparatus figure, to
appear in Phys. Rev.
Coulomb Blockade of Tunneling Through a Double Quantum Dot
We study the Coulomb blockade of tunneling through a double quantum dot. The
temperature dependence of the linear conductance is strongly affected by the
inter-dot tunneling. As the tunneling grows, a crossover from
temperature-independent peak conductance to a power-law suppression of
conductance at low temperatures is predicted. This suppression is a
manifestation of the Anderson orthogonality catastrophe associated with the
charge re-distribution between the dots, which accompanies the tunneling of an
electron into a dot. We find analytically the shapes of the Coulomb blockade
peaks in conductance as a function of gate voltage.Comment: 11 pages, revtex3.0 and multicols.sty, 4 figures uuencode
Transport in Coupled Quantum Dots: Kondo Effect Versus Anti-Ferromagnetic Correlation
The interplay between the Kondo effect and the inter-dot magnetic interaction
in a coupled-dot system is studied. An exact result for the transport
properties at zero temperature is obtained by diagonalizing a cluster, composed
by the double-dot and its vicinity, which is connected to leads. It is shown
that the system goes continuously from the Kondo regime to an
anti-ferromagnetic state as the inter-dot interaction is increased. The
conductance, the charge at the dots and the spin-spin correlation are obtained
as a function of the gate potential.Comment: 4 pages, 3 postscript figures. Submitted to PR
Search for antihelium in cosmic rays
The Alpha Magnetic Spectrometer (AMS) was flown on the space shuttle
Discovery during flight STS-91 in a 51.7 degree orbit at altitudes between 320
and 390 km. A total of 2.86 * 10^6 helium nuclei were observed in the rigidity
range 1 to 140 GV. No antihelium nuclei were detected at any rigidity. An upper
limit on the flux ratio of antihelium to helium of < 1.1 * 10^-6 is obtained.Comment: 18 pages, Latex, 9 .eps figure
- âŠ