Performance of a Modified Rabbit Model of Abdominal Aortic Aneurysm Induced by Topical Application of Porcine Elastase: 5-Month Follow-up Study

AbstractObjectivesTo modify the method for creating an abdominal aortic aneurysm in rabbits, and to study its performance.Materials and methodsA total of 24 New Zealand white rabbits were induced topically with 10 μl of porcine elastase (0, 0.1, 5 and 10 units μl−1) to define the optimal concentration (groups A–D). Twelve aneurysms were induced with 10 units μl−1 of 10 μl elastase to serve as a follow-up group (group E) to serve as a follow-up. A 1.5-cm aortic segment was isolated and induced with elastase solution for 30 min.ResultsAll animals in groups D and E developed AAA by day 5. Aneurysms in Group E were stable over 100 days. Partial destruction to disappearance of elastic lamellae and smooth muscle cells (SMCs) was seen in elastase-treated animals by day 5. Regenerated elastin and proliferated SMCs were present in group E. Matrix metalloproteinases 2 and 9 and RAM11 showed strong expression in group D, but expression decreased in group E after day 15.ConclusionsThe rabbit AAA model induced via topical application of porcine elastase at 10 units μl−1 for 30 min appears easy and simple, with shorter induction and more rapid aortic dilation. The model is stable over 100 days and is useful to study the formation and progress of AAAs

Data-driven Modeling of a Coronal Magnetic Flux Rope: from Birth to Death

Magnetic flux ropes are a bundle of twisted magnetic field lines produced by internal electric currents, which are responsible for solar eruptions and are the major drivers of geomagnetic storms. As such, it is crucial to develop a numerical model that can capture the entire evolution of a flux rope, from its birth to death, in order to predict whether adverse space weather events might occur or not. In this paper, we develop a data-driven modeling that combines a time-dependent magneto-frictional approach with a thermodynamic magnetohydrodynamic model. Our numerical modeling successfully reproduces the formation and confined eruption of an observed flux rope, and unveils the physical details behind the observations. Regarding the long-term evolution of the active region, our simulation results indicate that the flux cancellation due to collisional shearing plays a critical role in the formation of the flux rope, corresponding to a substantial increase in magnetic free energy and helicity. Regarding the eruption stage, the deformation of the flux rope during its eruption can cause an increase in the downward tension force, which suppresses it from further rising. This finding may shed light on why some torus-unstable flux ropes lead to failed eruptions after large-angle rotations. Moreover, we find that twisted fluxes can accumulate during the confined eruptions, which would breed the subsequent eruptive flares.Comment: 30 pages, 10 figures, Accepted for Ap

Suppression of Superconducting Critical Current Density by Small Flux Jumps in MgB2MgB_2 Thin Films

By doing magnetization measurements during magnetic field sweeps on thin films of the new superconductor $MgB_2$, it is found that in a low temperature and low field region small flux jumps are taking place. This effect strongly suppresses the central magnetization peak leading to reduced nominal superconducting critical current density at low temperatures. A borderline for this effect to occur is determined on the field-temperature (H-T) phase diagram. It is suggested that the small size of the flux jumps in films is due to the higher density of small defects and the relatively easy thermal diffusion in thin films in comparison with bulk samples.Comment: 7 figures Phys. Rev. B accepted scheduled issue: 01 Feb 200

Multi-Band Exotic Superconductivity in the New Superconductor Bi4O4S3

Resistivity, Hall effect and magnetization have been investigated on the new superconductor Bi4O4S3. A weak insulating behavior has been induced in the normal state when the superconductivity is suppressed. Hall effect measurements illustrate clearly a multiband feature dominated by electron charge carriers, which is further supported by the magnetoresistance data. Interestingly, a kink appears on the temperature dependence of resistivity at about 4 K at all high magnetic fields when the bulk superconductivity is completely suppressed. This kink can be well traced back to the upper critical field Hc2(T) in the low field region, and is explained as the possible evidence of residual Cooper pairs on the one dimensional chains.Comment: 5 pages, 5 figure

Relic Gravitational Waves And CMB Polarization In The Accelerating Universe

In this paper we briefly present our works on the relic gravitational waves (RGW) and the CMB polarization in the accelerating universe. The spectrum of RGW has been obtained, showing the influence of the dark energy. Compared with those from non-accelerating models, the shape of the spectrum is approximately similar, nevertheless, the amplitude of RGW now acquires a suppressing factor of the ratio of matter over dark energy $\propto \Omega_m/\Omega_{\Lambda}\sim 0.4$ over almost the whole range of frequencies. The RGW spectrum is then used as the source to calculate the spectra of CMB polarization. By a two half Gaussian function as an approximation to the visibility function during the photon decoupling, both the "electric" and "magnetic" spectra have been analytically derived, which are quite close to the numerical ones. Several physical elements that affect the spectra have been examined, such as the decoupling process, the inflation, the dark energy, the baryons, etc.Comment: 28 pages, 11 figures,accepted by IJMPD, Vol 17, No.7 (2008) 1005-112

Muon-spin rotation and magnetization studies of chemical and hydrostatic pressure effects in EuFe_{2}(As_{1-x}P_{x})_{2}

The magnetic phase diagram of EuFe$_{2}$(As$_{1-x}$P$_{x}$)$_{2}$ was investigated by means of magnetization and muon-spin rotation studies as a function of chemical (isovalent substitution of As by P) and hydrostatic pressure. The magnetic phase diagrams of the magnetic ordering of the Eu and Fe spins with respect to P content and hydrostatic pressure are determined and discussed. The present investigations reveal that the magnetic coupling between the Eu and the Fe sublattices strongly depends on chemical and hydrostatic pressure. It is found that chemical and hydrostatic pressure have a similar effect on the Eu and Fe magnetic order.Comment: 11 pages, 10 figure

Engineering Colloidal Metal-Semiconductor Nanorods Hybrid Nanostructures for Photocatalysis

Comprehensive Summary Emerging engineering strategies of colloidal metal-semiconductor nanorod hybrid nanostructures spanning from type, size, dimension, and location of both metal nanoparticles and semiconductors, co-catalyst, band gap structure, surface ligand to hole scavenger are elaborated symmetrically to rationalize the design of this type of intriguing materials for efficient photocatalytic applications. This article is protected by copyright. All rights reserved