Mitochondrial variation of the "eyed" turtles (Sacalia) based on known-locality and trade specimens

Bryan L. Stuart is thanked for his hard work to collect wild specimens, as well as providing insightful and useful comments on the data. We thank Abigail Wolf of the Field Museum for providing photographs of specimens. Robert Murphy of the Royal Ontario M

Optical properties of aluminum-, gallium-, and indium-doped Bi4Ti3O12 thin films

Undoped and Al-, Ga-, and In-doped Bi4Ti3O12 thin films were prepared on fused quartz substrates by chemical solution deposition. Their microstructures and optical properties were investigated by x-ray diffraction and UV-visible-NIR spectrophotometer, respectively. The optical band-gap energies, Urbach energies, and linear refractive indices of all the films are derived from the transmittance spectrum. Following the single oscillator model, the dispersion parameters such as the average oscillator energy (E-0) and dispersion energy (E-d) are achieved. The energy band gap and refractive indices are found to decrease with introducing the dopants of Al, Ga, and In, which is useful for the band-gap engineering and optical waveguide devices. The refractive index dispersion parameter (E-0/S-0) increases and the chemical bonding quantity (beta) decreases in all the films compared with those of bulk. It is supposed to be caused by the nanosize grains in films. (c) 2009 American Institute of Physics. [DOI 10.1063/1.3138813]

In-Situ Boron and Aluminum Doping and Their Memory Effects in 4H-SiC Homoepitaxial Layers Grown by Hot-Wall LPCVD

The in-situ p-type doping of 4H-SiC grown on off-oriented (0001) 4H-SiC substrates was performed with trimethylaluminum (TMA) and/or diborane (B2H6) as the dopants. The incorporations of Al and B atoms and their memory effects and the electrical properties of p-type 4H-SiC epilayers were characterized by secondary ion mass spectroscopy (SIMS) and Hall effect measurements, respectively. Both Al- and B-doped 4H-SiC epilayers were p-type conduction. It was shown that the profiles of the incorporated boron and aluminum concentration were in agreement with the designed TMA and B2H6 flow rate diagrams. The maximum hole concentration for the Al doped 4H-SiC was 3.52x10(20) cm(-3) with Hall mobility of about 1 cm(2)/Vs and resistivity of 1.6 similar to 2.2x10(-2) Omega cm. The heavily boron-doped 4H-SiC samples were also obtained with B2H6 gas flow rate of 5 sccm, yielding values of 0.328 Omega cm for resistivity, 5.3x10(18) cm(-3) for hole carrier concentration, and 7 cm(2)/VS for hole mobility. The doping efficiency of Al in SiC is larger than that of B. The memory effects of Al and B were investigated in undoped 4H-SiC by using SIMS measurement after a few run of doped 4H-SiC growth. It was clearly shown that the memory effect of Al is stronger than that of B. It is suggested that p-type 4H-SiC growth should be carried out in a separate reactor, especially for Al doping, in order to avoid the join contamination on the subsequent n-type growth. 4H-SiC PiN diodes were fabricated by using heavily B doped epilayers. Preliminary results of PiN diodes with blocking voltage of 300 V and forward voltage drop of 3.0 V were obtained.

Enolic Schiff base aluminum complexes and their catalytic stereoselective polymerization of racemic lactide

A series of enolic Schiff base aluminum(III) complexes LAIR (where L = NNOO-tetradentate enolic Schiff base ligand) containing ligands that differ in their steric and electronic properties were synthesized. Their single crystals showed that these complexes are five -coordinated around the aluminum center. Their coordination geometries are between square pyramidal and trigonal bipyramidal. Their catalytic properties in the solution polymerization of racemic lactide (rac-LA) were examined. The modifications in the auxiliary ligand exhibited a dramatic influence on the catalytic performance.

Enolic Schiff-base aluminum complexes and their application in lactide polymerization

A series of NNOO-tetradentate enolic Schiff-base ligands were prepared where ligand L-1 = bis(benzoylacetone)propane-1,2-diimine, L-2 = bis(acetylacetone)-propane-1,2-diimine, L-3 = bis-(acetylacetone)cyclohexane-1,2-diimine. Their further reaction with aluminum tris(ethyl) formed complexes LAlEt (1a, 2a and 3a). The solid structure of complexes la, 2a and 3a confirmed by X-ray single crystal analysis manifested that these complexes were all monomeric and five-coordinated with an aluminum atom in the center. The configurations of these complexes varied from trigonal bipyramidal geometry (tbp) to square pyramidal geometry (sqp) due to their different auxiliary ligand architectures. H-1 NMR spectra indicated that all these complexes retained their configuration in solution states. Their catalytic properties to polymerize racemic-lacticle (rac-LA) in the presence of 2-propanol were also studied. The diimine bridging parts as well as the diketone segment substituents had very close relationship with their performance upon the polymerization process. All these complexes gave moderately isotactic polylactides with controlled molecular weight and very narrow molecular weight distributions.