Bican Bey

Musahip'in İstiklal'de tefrika edilen Bican Bey adlı romanıSüreli yayın kapandığından tefrika yarım kalmıştır

IN SITU VASCULAR TISSUE REMODELING USING BIODEGRADABLE TUBULAR SCAFFOLDS WITH INCORPORATED GROWTH FACTORS AND CHEMOATTRACTANT MOLECULES

Background Currently, the search for the bioactive molecules capable of promoting formation of the vascular tissue is still ongoing. We have previously demonstrated that incorporation of the growth factors and chemoattractant molecules into the biodegradable tubular scaffolds can increase their primary patency upon the implantation into rat abdominal aorta. However, further studies are required to investigate tissue remodeling using functionalized vascular grafts with the same diameter as a replaced native vessel. Aim To investigate the specific aspects of de novo vascular tissue formation and calcification employing rat abdominal aorta interposition model and vascular grafts with 1.5 mm diameter with incorporated vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and stromal cell-derived factor (SDF)-1α. Methods Tubular grafts with a diameter of 1.5 mm were blended of poly(3-hydroxybutyrateco-3-hydroxyvalerate) and poly(ε-caprolactone) (PHBV/PCL). Grafts without growth factors were fabricated using standard electrospinning technique whilst grafts with incorporated growth factors were prepared utilizing emulsion electrospinning. VEGF was incorporated into the inner third, whereas bFGF and SDF-1α were incorporated into the outer two-thirds of the graft. Grafts were implanted into the abdominal aortas of Wistar rats for 1, 3, 6, and 12 months following scanning electron microscopy along with histological and immunofluorescent examination. Results Primary patency of the grafts with VEGF, bFGF, and SDF-1α reached 93% indicative of structural integrity of the vascular tissue. Neither signs of inflammation nor severe calcification was detected. Conclusion As in 2 mm diameter vascular grafts, incorporation of bioactive factors into 1.5 mm diameter grafts increased their long-term primary patency and improved vascular tissue formation in comparison with non-modified grafts.  Background Currently, the search for the bioactive molecules capable of promoting formation of the vascular tissue is still ongoing. We have previously demonstrated that incorporation of the growth factors and chemoattractant molecules into the biodegradable tubular scaffolds can increase their primary patency upon the implantation into rat abdominal aorta. However, further studies are required to investigate tissue remodeling using functionalized vascular grafts with the same diameter as a replaced native vessel. Aim To investigate the specific aspects of de novo vascular tissue formation and calcification employing rat abdominal aorta interposition model and vascular grafts with 1.5 mm diameter with incorporated vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and stromal cell-derived factor (SDF)-1α. Methods Tubular grafts with a diameter of 1.5 mm were blended of poly(3-hydroxybutyrateco-3-hydroxyvalerate) and poly(ε-caprolactone) (PHBV/PCL). Grafts without growth factors were fabricated using standard electrospinning technique whilst grafts with incorporated growth factors were prepared utilizing emulsion electrospinning. VEGF was incorporated into the inner third, whereas bFGF and SDF-1α were incorporated into the outer two-thirds of the graft. Grafts were implanted into the abdominal aortas of Wistar rats for 1, 3, 6, and 12 months following scanning electron microscopy along with histological and immunofluorescent examination. Results Primary patency of the grafts with VEGF, bFGF, and SDF-1α reached 93% indicative of structural integrity of the vascular tissue. Neither signs of inflammation nor severe calcification was detected. Conclusion As in 2 mm diameter vascular grafts, incorporation of bioactive factors into 1.5 mm diameter grafts increased their long-term primary patency and improved vascular tissue formation in comparison with non-modified grafts

Stable and metastable quasicrystals in Al-based alloy systems with transition metals

Quasiperiodic phases or quasicrystals (QC) with symmetries 5 and 10 have been found in numerous alloy systems of Al with d-transition metals (TM). Apart from QCs, related periodic phases with complicated structures were also discovered in these systems. QCs are usually formed in the Al-rich regions between 60 and 85 at. % Al. In binary Al-TM systems (TM = V, Cr, Mn, Fe, Co, Ni; Mo, Ru, Rh, Pd; W, Re, Os, Ir, Pt), they are metastable and can be produced by rapid solidification. Binary QCs can be stabilized in a number of ternary alloy systems such as Al-Ni-(Fe, Co, Ru, Rh), Al-Cu-(Fe, Co, Ru, Rh) and Al-Pd-(Mn, Re). Some aspects of the systematics of their formation are discussed. (C) 2003 Elsevier B.V. All rights reserved

Formation of Quasicrystals and Related Structures in Systems of Aluminum with Transition Metals. 2. Binary Systems Formed by Aluminum with 4d and 5d Metals

Numerous systems for aluminum with transition metals have been found to contain quasiperiodic phases (guasicrystals) having symmetries forbidden by classical crystallography. These phases are metastable in binary systems and have been obtained by rapid cooling from the liquid or gaseous phases. Binary quasicrystals are considered along with revised phase diagrams for the systems Al-4d-M and Al-5d-M (M from Mo to Pd and from W to Pt)

An investigation of the Al-Pd-Fe phase diagram between 50 and 100at.% Al:reaction scheme

The liquidus and solidus surfaces of Al-Pd-Fe were determined between 50 and 100 at.% Al. Fifteen ternary reactions involving the liquid phase were revealed: seven peritectic and eight transition reactions. The lowest temperature of the liquid phase corresponds to the binary Al-Pd eutectic. We also report on the five solid-state four-phase transformations in this compositional range from 750 degrees C up to subsolidus temperatures. (c) 2004 Elsevier B.V. All rights reserved

Decagonal quasicrystals of a new structural type

A stable decagonal phase of a new structural type was discovered in Al-Pd-Re. This is the second Al-based alloy system after Al-Pd-Mn where both stable icosahedral and decagonal phases are formed. In contrast to the isostructural icosahedral phases of similar Al and Pd concentrations in both systems, the new decagonal phase exhibits periodicity of similar to2.57 vs. similar to1.25 nm in Al-Pd-Mn and is formed at significantly higher Al concentration than that in Al-Pd-Mn. In the tenfold plane, the structural unit of the Al-Pd-Re decagonal phase assumed from the high-resolution electron images is tau times larger in diameter than that in Al-Pd-Mn

Monoclinic Al2Fe phase, its equilibrium and nonequilibrium formation

The diffraction pattern of Al2Fe can be readily indexed using a C-centred monoclinic structure with a = 0.4846 nm, b = 1.6745 nm, c = 0.7565 nm, and beta = 122.67degrees. The suggestion of peritectoid formation reaction of Al2Fe cannot be confirmed by means of the microstructural investigation of the as-cast samples and, at the same time, this contradicts the DTA results. Nonequilibrium solidification is therefore applied for explanation of this disagreement

Study of phase equilibria in the Al-Pd-Re system

Scanning and transmission electron microscopy have been combined with x-ray diffraction to examine the phase equilibria in the Al-Pd-Re system at 1000 degrees C for compositions front 50 to 100 at. % Al, and the corresponding isothermal section has been constructed. The binary monoclinic Al3Re phase has been observed for the first time. It is confirmed that there is a stable icosahedral phase in this system. The boundaries to its homogeneity region have been determined and the phase equilibria in which it participates