1,603 research outputs found
Acetylsalicylic acid reduces the severity of dextran sodium sulfate-induced colitis and increases the formation of anti-inflammatory lipid mediators
The role of non-steroidal anti-inflammatory drugs in inflammatory bowel disease is controversial, as they have been implicated in disease aggravation. Different from other cyclooxygenase inhibitors, acetylsalicylic acid (ASA) enhances the formation of anti-inflammatory and proresolution lipoxins derived from arachidonic acid as well as resolvins from omega-3 polyunsaturated fatty acids such as docosahexaenoic acid (DHA). In this study, we examined the effect of ASA on murine dextran sodium sulfate colitis. A mouse magnetic resonance imaging (MRI) protocol and post mortem assessment were used to assess disease severity, and lipid metabolites were measured using liquid chromatography-coupled tandem mass spectrometry. Decreased colitis activity was demonstrated by phenotype and MRI assessment in mice treated with ASA, and confirmed in postmortem analysis. Analysis of lipid mediators showed sustained formation of lipoxin A4 and an increase of DHA-derived 17-hydroxydocosahexaenoic acid (17-HDHA) after treatment with ASA. Furthermore, in vitro experiments in RAW264.7 murine macrophages demonstrated significantly increased phagocytosis activity after incubation with 17-HDHA, supporting its proresolution effect. These results show a protective effect of ASA in a murine colitis model and could give a rationale for a careful reassessment of ASA therapy in patients with inflammatory bowel disease and particularly ulcerative colitis, possibly combined with DHA supplementation
Magnetic properties of a new molecular-based spin-ladder system: (5IAP)2CuBr4*2H2O
We have synthesized and characterized a new spin-1/2 Heisenberg
antiferromagnetic ladder: bis 5-iodo-2-aminopyridinium tetrabromocuprate(II)
dihydrate. X-ray diffraction studies show the structure of the compound to
consist of well isolated stacked ladders and the interaction between the Cu(2+)
atoms to be due to direct Br...Br contacts. Magnetic susceptibility and
magnetization studies show the compound to be in the strong-coupling limit,
with the interaction along the rungs (J' ~ 13 K) much greater than the
interaction along the rails (J ~ 1 K). Magnetic critical fields are observed
near 8.3 T and 10.4 T, respectively, establishing the existence of the energy
gap.Comment: 10 pages, 4 figures, submitted to Phys. Rev. B Figure 4 did not
print. *.eps files replaced with figures.ps fil
Generalized Farey trees, transfer Operators and phase transitions
We consider a family of Markov maps on the unit interval, interpolating
between the tent map and the Farey map. The latter map is not uniformly
expanding. Each map being composed of two fractional linear transformations,
the family generalizes many particular properties which for the case of the
Farey map have been successfully exploited in number theory. We analyze the
dynamics through the spectral analysis of generalized transfer operators.
Application of the thermodynamic formalism to the family reveals first and
second order phase transitions and unusual properties like positivity of the
interaction function.Comment: 39 pages, 10 figure
Transport properties of clean and disordered superconductors in matrix field theory
A comprehensive field theory is developed for superconductors with quenched
disorder. We first show that the matrix field theory, used previously to
describe a disordered Fermi liquid and a disordered itinerant ferromagnet, also
has a saddle-point solution that describes a disordered superconductor. A
general gap equation is obtained. We then expand about the saddle point to
Gaussian order to explicitly obtain the physical correlation functions. The
ultrasonic attenuation, number density susceptibility, spin density
susceptibility and the electrical conductivity are used as examples. Results in
the clean limit and in the disordered case are discussed respectively. This
formalism is expected to be a powerful tool to study the quantum phase
transitions between the normal metal state and the superconductor state.Comment: 9 page
Vectorial bending characteristics of long-period grating written in D-shaped fibre
The curvature- or bend-sensing response of long-period gratings (LPG) UV-inscribed in D-shaped fiber has been investigated experimentally. Strong fiber orientation dependence of the spectral response when such LPGs are subjected to dynamic bending has been observed and is shown to form the basis for new vector sensors
Longitudinal and transverse fermion-boson vertex in QED at finite temperature in the HTL approximation
We evaluate the fermion-photon vertex in QED at the one loop level in Hard
Thermal Loop approximation and write it in covariant form. The complete vertex
can be expanded in terms of 32 basis vectors. As is well known, the
fermion-photon vertex and the fermion propagator are related through a
Ward-Takahashi Identity (WTI). This relation splits the vertex into two parts:
longitudinal (Gamma_L) and transverse (Gamma_T). Gamma_L is fixed by the WTI.
The description of the longitudinal part consumes 8 of the basis vectors. The
remaining piece Gamma_T is then written in terms of 24 spin amplitudes.
Extending the work of Ball and Chiu and Kizilersu et. al., we propose a set of
basis vectors T^mu_i(P_1,P_2) at finite temperature such that each of these is
transverse to the photon four-momentum and also satisfies T^mu_i(P,P)=0, in
accordance with the Ward Identity, with their corresponding coefficients being
free of kinematic singularities. This basis reduces to the form proposed by
Kizilersu et. al. at zero temperature. We also evaluate explicitly the
coefficient of each of these vectors at the above-mentioned level of
approximation.Comment: 13 pages, uses RevTe
The Transformation from Translucent into Transparent Rare Earth Ions Doped Oxyfluoride Glass-Ceramics with Enhanced Luminescence
Article reporting a scenario where a translucent Er3+−Yb3+ doped oxyfluoride precursor glass-ceramic (P-GC) becomes transparent with increasing crystal size and crystallinity
Low energy pre-blended mortars: Part 2 – Production and characterisation of mortars using a novel lime drying technique
The presence of free water in mortars destined for silo or bagged storage can lead to the degradation of the binder phase. Such water may be present as a result of using wet, as-delivered sand or as a consequence of prior processes such as de-activation of Roman cement. Thus, water must be removed from the system prior to storage. Part 1 of this paper describes the control of a technique by which quicklime is added to the wet system which principally dries it by both slaking the quicklime and evaporation as a consequence of the exothermic slaking reaction. Two examples of mortars are presented in which excess water is removed from the system by the inclusion of quicklime. In the first, the water is present in the as-delivered sand and the binder is a combination of the slaked lime and ggbs. In the second, the water remains after pre-hydration of a Roman cement which is a process to retard its rapid
setting characteristics. It is shown that optimally dried mortars are not subject to degradation following storage of both mortar types
- …