Delamination is a critical form of failure in composite laminates which is partitioned into a combination of three pure modes namely; opening, shearing and tearing (modes I, II and III respectively). Each fracture mode contributes to the total energy required for delamination growth, due to a combination of the different damage mechanisms that occur under each mode 1-2 . To formulate reliable m...

We present an experimental and theoretical study of the optical excitation of long-range surface polaritons supported by thin layers of amorphous silicon (a-Si). The large imaginary part of the dielectric constant of a-Si at visible and ultraviolet (UV) frequencies allows the excitation of surface polariton modes similar to long-range surface plasmon polaritons on metals. Propagation of these m...

The upper airway of obstructive sleep apnoea patients is subjected to recurrent negative pressure swings promoting its collapse and reopening. The aim of the present study was to ascertain whether this mechanical stress induces upper airway inflammation in a rat model. The upper airway of Sprague-Dawley rats was subjected to a periodic pattern of recurrent negative (-40 cmH2O, 1 s) and positive...

After extensive studies spanning over half a century, there is little consensus on the kinetic mechanism of DNA polymerases. Using stopped-flow fluorescence assays for mammalian DNA polymerase beta (Pol beta), we have previously identified a fast fluorescence transition corresponding to conformational closing, and a slow fluorescence transition matching the rate of single-nucleotide incorporati...

The ring-opening reaction of a trifluorinated indolylfulgide has been studied as a function of temperature and optical pre-excitation where it was found that reaction times decreased as temperature increased from 10.3 ps at 12 degrees C to 7.6 ps at 60 degrees C. Simultaneously, the quantum yields for the ring-opening reaction grew from 3.1% (12 degrees C) to 5.0% (60 degrees C). When the react...

Much debate surrounds how prosurvival members of the BCL-2 family repress opening of the BAX/BAK channel to block apoptosis; in this issue Llambi et al. (2011) identify two modes of apoptosis inhibition that exhibit surprisingly different behavior upon repeat proapoptotic challenges by BH3-only proteins.

We present experimental observations of visible wavelength second- and third-harmonic generation on single plasmonic nanowires of variable widths. We identify that near-infrared surface plasmon polaritons, which are guided along the nanowire, act as the source of the harmonics generation. We discuss the underlying mechanism of this nonlinear process, using a combination of spatially resolved me...

Due to architectural, mechanical and even structural considerations, in some cases there is need to create some openings in the composite steel shear walls. Presence of the openings can considerably affect the wall behavior. Therefore in this study, the effects of the opening on the behavior of composite steel shear walls are investigated. For this purpose, first an experimental specimen withou...

sudden fracture is one of the major failure modes in brittle materials. plexiglass (polymethyl methacrylate) is a well known brittle polymer, widely used in various industries. many types of notches, particularly v-shaped notches, are sometimes used in the components made of plexiglass. these notches can dramatically decrease the load bearing capacity of components due to the concentration of s...

Influenza virus hemagglutinin (HA), a homotrimeric integral membrane glycoprotein essential for viral infection, is engaged in two biological functions: recognition of target cells' receptor proteins and fusion of viral and endosomal membranes, both requiring substantial conformational flexibility from the part of the glycoprotein. The different modes of collective motions underlying the functi...