Magnetically aligned carbon nanotube in nanopaper enabled shape-memory nanocomposite for high speed electrical actuation

A new shape-memory nanocomposite that exhibits rapid electrical actuation capabilities is fabricated by incorporating self-assembly multiwalled carbon nanotube (MWCNT) nanopaper and magnetic CNTs into a styrene-based shape-memory polymer (SMP). The MWCNT nanopaper was coated on the surface to give high electrical conductivity to SMP. Electromagnetic CNTs were blended with and, vertically aligned into the SMP resin upon a magnetic field, to facilitate the heat transfer from the nanopaper to the underlying SMP. This not only significantly enhances heat transfer but also gives high speed electrical actuation

Genetic Diversity of Salmonella enteric serovar Typhi and Paratyphi in Shenzhen, China from 2002 through 2007

<p>Abstract</p> <p>Background</p> <p>Typhoid and paratyphoid fever are endemic in China. The objective of this investigation was to determine the molecular features of nalidixic acid-resistant <it>Salmonella enteric </it>serovar Typhi (<it>S. typhi</it>) and Paratyphi (<it>S. paratyphi</it>) from blood isolates in Shenzhen, China.</p> <p>Results</p> <p>Twenty-five <it>S. typhi </it>and 66 <it>S. paratyphi </it>were isolated from 91 bacteriemic patients between 2002 and 2007 at a hospital in Shenzhen, Southern China. Fifty-two percent (13/25) of <it>S. typhi </it>and 95.3% (61/64) of <it>S. paratyphi </it>A were resistant to nalidixic acid. Sixty-seven isolates of nalidixic acid-resistant <it>Salmonella </it>(NARS) showed decreased susceptibility to ciprofloxacin (MICs of 0.125-1 μg/mL). All 75 NARS isolates had a single substitution in the quinolone resistance-determining region (QRDR) of GyrA (Ser83→Phe/Pro/Tyr, or Asp87→Gly/Asn), and 90.7% of these isolates carried the substitution Ser83Phe in GyrA. No mutation was found in the QRDR of <it>gyrB</it>, <it>parC</it>, or <it>parE</it>. Plasmid mediated quinolone resistance genes including <it>qnr </it>and <it>aac(6')-Ib-cr </it>were not detected in any isolate. Twenty-two distinct pulsed field gel electrophoresis (PFGE) patterns were observed among <it>S. typhi</it>. Sixty-four isolates of <it>S. paratyphi </it>A belonged to one clone. Eighty-seven investigated inpatients were infected in the community. Six patients infected by <it>S. paratyphi </it>A had a travel history before infection.</p> <p>Conclusions</p> <p>Nalidixic acid-resistant <it>S. typhi </it>and <it>S. paratyphi </it>A blood isolates were highly prevalent in Shenzhen, China. PFGE showed the variable genetic diversity of nalidixic acid-resistant <it>S. typhi </it>and limited genetic diversity of nalidixic acid -resistant <it>S. paratyphi </it>A.</p

Cooperative dynamics of heuristic swelling and inhibitive micellization in double-network hydrogels by ionic dissociation of polyelectrolyte

In this study, a cooperative model has been proposed for the double network (DN) hydrogel, which synchronously undergoes heuristic swelling and inhibitive micellization by the ionic dissociation of polyelectrolyte. Flory-Huggins solution theory is initially employed to identify the working mechanism of dielectric constants on swelling behavior of the DN hydrogel. Then a free-energy function is introduced to formulate the constitutive relationship of the DN hydrogels, in which the first hydrotropic network undergoes a heuristic swelling and the second hydrophobic network undergoes an inhibitive micellization. Finally, the proposed model has been verified using the experimental results reported in the literature. A good agreement between the theoretical results and experimental ones has been achieved. This study provides a fundamental approach to formulate the constitutive relationship and to understand the cooperative dynamics of two types of networks in DN hydrogels induced by the polyelectrolyte