Higher order structures and toughening mechanisms for simultaneously polymerized polymethacrylate/polyurethane

Amorphous polymer/crystalline polymer blends can be prepared via the simultaneous polymerization of polymethacrylate/polyurethane combinations. The relationship between higher order structures and fracture mechanisms in these blends must be uncovered to elucidate the source of the increased fracture toughness of such materials. The present work involves the production of blended polymethacrylate/polyurethane and assess the internal structures of these specimens using optical and electron microscopy. These observations reveal the presence of both spherulites and elastomeric phases. The spherulites consisting of the polyurethane and are several micrometers in diameter whereas the phase-separated polyurethane elastomeric domains are approximately 100 nm in size. Multiple cracks, crack bridging and plastic deformation around the precrack tips of loaded specimens are evidently responsible for the increased toughness of these blends. The former two phenomena are attributed to the presence of spherulites while the plastic deformation of the methacrylate matrix is ascribed to cavitation of the polyurethane elastomeric phases in response to loading.     

Detection of the leghemoglobin gene on two chromosomes of Phaseolus vulgaris by in situ PCR linked-fluorescent in situ hybridization (FISH)

OBJECTIVE: To investigate the effect of phentolamine, a sympathetic blocking agent, on the spontaneous electrical activity (SEA) recorded from a locus of a myofascial trigger spot (MTrS), equivalent to a human trigger point, in rabbit skeletal muscle. DESIGN: Randomized control trial. SETTING: A university medical laboratory. PATIENTS OR OTHER PARTICIPANTS: Nine adult New Zealand rabbits. INTERVENTION: In the experimental group phentolamine mesylate (1mg/kg) was injected into the external iliac artery, followed by flushing with normal saline. The control group was treated with normal saline instead of phentolamine using the same procedure. MAIN OUTCOME MEASURES: SEA was recorded from multiple active loci of MTrSs in the biceps femoris muscle: initially SEA in the same locus was recorded before and immediately after phentolamine (or normal saline) injection; then SEA was recorded from 25 different active loci. The mean of the average integrated signal (AIS) of SEA was analyzed, comparing the effects of phentolamine and normal saline on SEA. RESULTS: In the same active locus, the AIS of SEA showed statistically a linear decay with time after phentolamine injection, with a correlation coefficient of .56 at p < .05. However, no statistical relationship could be derived for the control group data with time by using regression analysis, probably because of large variations among the rabbits and movement artifacts during the experiment. In 25 different loci in the phentolamine group, the mean of the AIS of SEA (7.92 microV) was significantly lower than that of the control group (9.89 microV) at p < .05. CONCLUSIONS: The results support the hypothesis that the autonomic nervous system is involved in the pathogenesis of myofascial trigger points. The application of the AIS as an evaluation index seems to be feasible in the quantitative measurement of SEA.     

Fabrication and evaluation of aluminum nitride based MEMS piezoelectric vibration sensors for large-amplitude vibration applications

Microsystem Technologies - In this work, we designed a novel structure to produce vibration sensors with a linear voltage output that are suitable for large-amplitude vibration applications....