Argon matrix, 12 K. 6 Absolute value of the angle between the IR transition moment and the * polarization direction. "Assigned as the C=C stretch. Calculated frequency, 1546 cm"1 (MNDO X 0.915), calculated c=c = 90°. unreacted 3 and, particularly at the higher temperatures, a stable product to which we assign the structure 4.7 The evidence for structure 1 is (i) a 1557-cm"1 band in the C=C stretching region, relatively weak in the IR (Figure 1), but the strongest of all the Raman bands. The shift relative to 5 (1685 cm"1) is compatible with strong double pyramidalization of 1. (ii) A broad UV band peaking at 245 ± 15 nm, compatible with the expected lowering of the * excitation energy. Irradiation at 248 nm bleaches both the UV and the IR bands associated with 1 and increases the IR peaks of 4; no additional products are detected, (iii) Above ~165 K in the neat sample, which is quite rigid, and already above ~40 K in the much less viscous argon-matrix-isolated sample, the IR bands of 1 gradually disappear and those of the known5 2 + 2 dimer of 1 grow; a GC comparison with an authentic sample (SE-30 column) confirms that the dimer is the chief product formed on warm-up.Synthesis and Characterization of High-Valent Oxo-Olefin and Oxo-Carbonyl Complexes. Crystal and Molecular Structure of W(0)Cl2(CH2=CH2)(PMePh2)2

Vascular endothelial growth factor (VEGF) is an effective growth and angiogenic cytokine, which stimulates proliferation and survival of endothelial cells, and promotes angiogenesis and vascular permeability. Binding VEGF with heparin could protect it from rapid degradation, subsequently allowing it to be controlled release. Primarily, poly(ε-caprolactone) (PCL) and keratin were coelectrospun, followed by conjugating with heparin and subsequently binding VEGF. The loaded heparin and VEGF on these mats were quantified, respectively. The surface characteristics of mats were investigated by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The VEGF delivery results indicated these mats could sustainably release VEGF for 2 weeks. Cell viability assays suggested these mats were valid to accelerate human umbilical vein endothelial cells (HUVECs) proliferation, while inhibit human umbilical arterial smooth muscle cells (HUASMCs) growth under the combined actions of VEGF and heparin. The results tested by blood clotting times (APTT, PT, and TT), hemolysis, and platelet adhesion indicated the mats were blood compatible. To sum up, these biocomposite mats are ideal scaffolds for vascular tissue engineering. K E Y W O R D S heparin, keratin, vascular tissue engineering, VEGF

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