Behavior of shock waves formed by unsteady supersonic jet injected into cell

The unsteady behavior of flow driven by a jet suddenly injected into a cell is numerically studied by solving the axisymmelric two-dimensional compressible Navier-Stokes equations. The system of the calculation is a model of the laser ablation of a certain duration followed by a discharging process through the exit hole at the down- stream end of the cell. In the calculations, the contour of the cell is changed while other parameters such as the Mach number of the jet, its duration, and the diameter of the cell exit are fixed. Monitoring the velocity at the exit hole is used to investigate the influence of the shape on the interaction between the shock wave and the jet. As the result, it was found that the velocity peak value and its arrival time at the downstream end of the cell exit are determined by the diameter of the cell.     

New bleeding model of additives in a polypropylene film under atmospheric pressure II

Many additives are commercially used to add more favorable qualities to films. The bleeding process by which the additive in a film comes to the surface is considered. A new bleeding model of additives in a polypropylene film under atmospheric pressure was investigated. Solubility and diffusion are found to be important for explaining this bleeding process. It was found that the experimental results were explained more precisely by assuming a two‐step transport process between the crystalline regions and the amorphous ones. The solubilities and diffusion coefficients of UV‐stabilizers such as 2‐(2H‐benzotriazol‐2‐yl)‐4‐(1,1,3,3‐tetramethylbutyl)phenol and 2‐(2H‐benzotriazol‐2‐yl)‐4‐methylphenol were determined at 40°C. The difference between the saturation solubilities and the diffusion coefficients of UV‐stabilizers was discussed by comparing with the results of molecular dynamics (MD) simulation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

High-speed and low-driving-Voltage thin-sheet X-cut LiNbO/sub 3/ Modulator with laminated low-dielectric-constant adhesive

We present a novel thin-sheet X-cut LiNbO/sub 3/ optical modulator structure which can be fabricated by precise polishing and lapping to obtain a thinner LiNbO/sub 3/ substrate for a lower driving voltage in addition to velocity matching and impedance matching. We demonstrated that the fabricated modulator had a driving voltage V/spl pi/ of 2 V and zero chirp for 40-Gb/s operation and had a high potential for suppressed dc drift, and long-term reliability.     

Morphological study on thermal treatment and degradation behaviors of solution-grown poly(l-lactide) single crystals

Morphological changes of solution-grown crystals (SGCs) of poly(l-lactide) (PLLA) following thermal treatment and enzymatic degradation were investigated using atomic force microscopy in terms of defects in the crystals. PLLA SGCs were grown from a dilute solution of acetonitrile at 5 °C. The obtained solution-grown monolamellar crystals have a lozenge-shaped morphology containing unique dimensions, with one side measuring 12 μm. To investigate enzymatic degradation behavior, PLLA SGCs were incubated in buffered solution with proteinase-K at 37 °C. The initial stage of enzymatic degradation of PLLA SGCs with proteinase-K occurs in loosely folding chains at the surface of the crystal. Thermally treated PLLA SGCs below the melting temperature showed an increase of the lamellar thickness of the SGCs at the treated temperature and partial surface erosion following enzyme exposure. These results indicate that less ordered chains exist throughout the lamellae and their thermal-induced chain extension makes them more susceptible to enzyme attack.     

A tetrameric dialdehyde formed in the reaction of butyral dehyde and benzylamine: A possible intermediary component for protein cross-linking induced by lipid oxidation

We investigated the reaction of butyraldehyde and benzylamine and analyzed the products to identify the components that produce protein cross-linking in the reaction of butyraldehyde and proteins. When the mixtures of butyraldehyde and benzylamine were incubated at pH 7 and 37°C for 48 hr, many reaction products other than 2-ethyl-2-hexenal and Schiff bases of butyraldehyde and 2-ethyl-2-hexenal were produced. Fluorescent substance(s) were formed only in the presence of dissolved oxygen in the reaction mixture. Three new nonflourescent products—d,e andf—were isolated, and their structures are suggested to be 2,9-dibenzyl-4,6,8-triethyl-7-propyl-2,9-diazabicyclo[3,3,1] nona-3-ene (d), 1-phenyl-2-benzyl- 4,5,7-triethyl-6-propyl-1H,2H,3H,5H,6H,7H,8H-pyrido[1,2-clpyrimidine (e) and 1-phenyl-2-benzyl-4,5,7-triethyl-6-propyl-1H,2H,4aH,5H,6H,7H,8H-pyrido[1,2-c]pyrimidine (f). Formation of these compounds suggested that the protein, cross-linking with butyraldehyde is caused by the tretrameric dialdehyde formed by repeated aldol condensation and Michael reaction of butyraldehyde.