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Poly(p-phenylene benzobisoxazole) (PBO) has been synthesized in the presence of singlewall carbon nanotubes (SWNTs) in poly(phosphoric acid) (PPA) using typical PBO polymerization conditions. PBO and PBO/SWNT lyotropic liquid crystalline solutions in PPA have been spun into fibers using dry-jet wet spinning. The tensile strength of the PBO/SWNT fiber containing 10 wt % SWNTs is about 50% higher than that of the control PBO fibers containing no SWNTs. The structure and morphology of these fibers have been studied.

Keyword: boron nitride nanotubesBoron nitride nanotubes (BNNTs) are desired for their exceptional mechanical, electronic, thermal, structural, textural, optical, and quantum properties. Golberg [1] gives an excellent review of possible applications. To date, BNNTs have been grown by a number of techniques which can be divided roughly into two categories based on the class of material produced.One is the high temperature category in which energy is concentrated into a B or BN target at a level which can vaporize elemental boron. BNNTs form in the deposits of the liberated vapors. The energy is input by laser [2][3][4][5][6] or by arc discharge [7][8][9] . Only small quantities (mg's) of material have been produced by this method, but the tubes are high quality. They have one or just a few walls, and most importantly, the tube walls are low in defects and parallel to the axis of the nanotube. The second category is low temperature synthesis, between about 600 C and 1700 C, well below the vaporization temperature of pure boron (~4000 C). These low temperature synthesis methods can be further divided into two catagories. In the first category, ball-milled precursor powders of boron and catalyst are annealed in a nitrogen or ammonia gas atmosphere, sprouting nanostructures on their

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This paper presents a theory of optimal debt structure when the moral hazard problem is severe. The main idea is that the optimal debt contract delegates monitoring to a single senior lender and that seniority allows the monitoring senior lender to appropriate the full return from his monitoring activities. The theory explains~i! why debt contracts are prioritized,~ii! why short-term debt is senior to long-term debt, and~iii! why financial intermediaries usually hold short-term senior debt whereas long-term junior debt is widely held. Another implication of the theory is that covenant and maturity structures will be set to conform to the seniority structure.

We propose a model linking consumer characteristics (consumer susceptibility to interpersonal influence and Internet shopping experience), attitude toward online reviews (perceived usefulness), and the outcome of online reviews (usage frequency and purchase influence). We advance hypotheses on the interrelationships among these factors and on the moderating effects of national culture on some of the relationships. We test the hypotheses on survey data collected from U.S. and Korean consumers. The results show that national culture has important moderating effects on the relationships among online reviews and its antecedents. The results suggest that an attitude-oriented marketing communication strategy is more effective for Korean consumers while a behavior-oriented strategy is more effective for U.S. consumers.

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