Improving the mechanical properties of single-walled carbon nanotube sheets by intercalation of polymeric adhesives

Organic polymers, such as poly(vinyl alcohol), poly(vinyl pyrrolidone), and poly(styrene), were intercalated into single-walled carbon nanotube sheets by soaking the sheets in polymer solutions. Even for short soak times, significant polymer intercalation into existing free volume was observed. Tensile tests on intercalated sheets showed that the Young\u27s modulus, strength, and toughness increased by factors of 3, 9, and 28, respectively, indicating that the intercalated polymer enhances load transmission between nanotubes

Electrically pumped continuous wave quantum dot lasers epitaxially grown on patterned, on-axis (001) Si

High performance III-V lasers at datacom and telecom wavelengths on on-axis (001) Si are needed for scalable datacenter interconnect technologies. We demonstrate electrically injected quantum dot lasers grown on on-axis (001) Si patterned with {111} v-grooves lying in the [110] direction. No additional Ge buffers or substrate miscut was used. The active region consists of five InAs/InGaAs dot-in-a-well layers. We achieve continuous wave lasing with thresholds as low as 36 mA and operation up to 80°C

Mechanical properties of nanotube sheets: Alterations in joint morphology and achievable moduli in manufacturable materials

Nanotube sheets, or “bucky papers,” have been proposed for use in actuating, structural and electrochemical systems, based in part on their potential mechanical properties. Here, we present results of detailed simulations of networks of nanotubes/ropes, with special emphasis on the effect of joint morphology. We perform detailed simulations of three-dimensional joint deformation, and use the results to inform simulations of two-dimensional (2D) networks with intertube connections represented by torsion springs. Upper bounds are established on moduli of nanotube sheets, using the 2D Euler beam-network simulations. Comparisons of experimental and simulated response for HiPco-nanotube and laser-ablated nanotube sheets, indicate that ∼2–30-fold increases in moduli may be achievable in these materials. Increasing the numbers of interrope connections appears to be the best target for improving nanotube sheet stiffnesses in materials containing straight segments. © 2004 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70283/2/JAPIAU-95-8-4335-1.pd

Highly conducting carbon nanotube/polyethyleneimine composite fibers

Single-walled carbon nanotube/ polyethyleneimine (SWNT/PEI) composite fibers are fabricated by coagulation-based spinning of SWNTs dispersed in aqueous solution by various surfactants. The spun SWNT/PEI composite fibers are either solid or hollow (see Figure), and have useful mechanical properties and over a hundred times the electrical conductivity of supertough SWNT/polyvinyl alcohol composite fibers.Partially supported by the Defense Advanced Research Projects Agency Grant MDA972-02-C-0005, the Texas Higher Education Coordinating Board Grant 009741-0130-2003, and the Robert A. Welch Foundation. E. M. acknowledges funding from MEC (Ramón y Cajal Program). B. G. K. acknowledges support from University IT Research Center Project.Peer reviewe

Custom Integrated Circuits

Contains reports on six research projects.U.S. Air Force - Office of Scientific Research (Contract F49620-84-C-0004)Analog Devices, Inc.Defense Advanced Research Projects Agency (Contract N00014-80-C-0622)National Science Foundation (Grant ECS83-10941

JCDredesigna

This study surveyed addictions counselors to determine factors that predict affirmative attitudes and behaviors with all clients and with gay, lesbian, and bisexual clients (GLB) in particular. Three factors were predictive with regard to all clients, and 5 factors were predictive with regard to GLB clients. Nonheterosexist organizational climate was the only factor predictive in both situations. The implications of these results are discussed with regard to practice, research, and training