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The present study investigates a suitable material, which is expected to have biocompatibility and to promote tissue regeneration. For this purpose, we have chosen chitin that was chemically modified by phosphorylation with high degree of substitution. The phosphorylated chitin (P-chitin) was synthesized using the [H.sub.3][PO.sub.4]/[P.sub.2] [O.sub.5] / [ET.sub.3] [PO.sub.4] / hexanol method. The structure of P-chitin was analyzed by FTIR, [.sup.31]P- and [.sup.13]C-NMR spectroscopic studies, scanning electron microscopy, and X-ray diffraction. The thermal properties of the P-chitin were also characterized by thermogravimetric analyses. The highly phosphorylated chitin derivatives prepared by this method were soluble in water and amorphous in nature. Thus, [H.sub.3][PO.sub.4]/[P.sub.2][O.sub.5]/[ET.sub.3][PO.sub.4]/hexanol method provides a versatile and alternative route for synthesis of P-chitin, which would be useful for biomedical applications. POLYM. ENG. SCI., 49:844-849, 2009.©2009 Society of Plastics Engineers, INTRODUCTION Chitin, a natural polymer, is the second most abundant organic resource on the earth next to cellulose. It is an exoskeleton of crustacean, cuticle of insects, and the cell [...]

A new study investigates the annealing effect of Schottky contacts on Pd, Ti and Ni/n-Al0.11Ga0.89 diodes.

A study was conducted on the characteristics and degradation of an InGaN/AlGaN double-heterostructure light-emitting diode (LED) grown by metalorganic chemical vapor deposition on a sapphire substrate. The results indicate that the growth of dark regions was responsible for the degradation of electrical and optical characteristics. Moreover, GaN-based LEDs on sapphire substrates exhibit longer lifetime than the ZnSe-based LEDs.

Studies of AlAs/GaAs distributed Bragg reflector structure shows quasiperiodic zigzag roughness, nonuniformity of thickness and the compositional transitions. The degraded heterointerfaces lead to lower reflectivity of the AlAs/GaAs distributed Bragg reflector on the silicon substrate. The reflector was grown by metalorganic chemical vapour deposition technique. Scanning electron and transmission electron microscopy and Auger electron spectroscopy were used.

The demonstration of GaN-based light-emitting diodes (LEDs) grown on template of 3C-SiC/Si(111) is presented and their structural properties are examined. The results have shown that using 3C-SiC as intermediate layer (IL) has helped in improving the performance of LEDs on silicon.

The characteristics of InGaN multiple quantum-well (MOW) green light emitting diodes (LEDs) on Si substrates grown by metal organic chemical vapor deposition are reported. The LED also exhibited a stable operation over 500 h under automatic current control (20 mA) condition at 27 degrees C.

A reflection model of two absorbing layers with a transparent substrate is used and the power reflectance of the AlGaN/GaN/sapphire heterostruture is numerically calculated. The analysis shows that reflectance measurement is undoubtedly feasible in determining the free exciton transition energy (E(Sub FX) of the AlGaN epilayer in the AlGaN/GaN heterostructure.