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Houston, TX, United States

Khantamat O.,Texas Center for Superconductivity | Li C.-H.,Texas Center for Superconductivity | Yu F.,Texas Center for Superconductivity | Jamison A.C.,Texas Center for Superconductivity | And 3 more authors.
ACS Applied Materials and Interfaces | Year: 2015

Catheter-related infections (CRIs) are associated with the formation of pathogenic biofilms on the surfaces of silicone catheters, which are ubiquitous in medicine. These biofilms provide protection against antimicrobial agents and facilitate the development of bacterial resistance to antibiotics. The application of photothermal agents on catheter surfaces is an innovative approach to overcoming biofilm-generated CRIs. Gold nanoshells (AuNSs) represent a promising photothermal tool, because they can be used to generate heat upon exposure to near-infrared (NIR) radiation, are biologically inert at physiological temperatures, and can be engineered for the photothermal ablation of cells and tissue. In this study, AuNSs functionalized with carboxylate-terminated organosulfur ligands were attached to model catheter surfaces and tested for their effectiveness at killing adhered Enterococcus faecalis (E. faecalis) bacteria. The morphology of the AuNSs was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), while the elemental composition was characterized by energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). Furthermore, optical and photothermal properties were acquired by ultraviolet-visible (UV-vis) spectroscopy and thermographic imaging with an infrared camera, respectively. Bacterial survival studies on AuNS-modified surfaces irradiated with and without NIR light were evaluated using a colony-formation assay. These studies demonstrated that AuNS-modified surfaces, when illuminated with NIR light, can effectively kill E. faecalis on silicone surfaces. © 2015 American Chemical Society. Source


Nyanteh Y.,University of Houston | Schneider N.,University of Houston | Schneider N.,University of Nottingham | Netter D.,University of Lorraine | And 4 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2015

High Temperature Superconducting (HTS) tapes based on YBCO are expected to reach a 4-fold critical current density improvement at 30 K and 3 T through developments currently underway at the University of Houston as part of an ARPA-e sponsored project. The major objective of this undertaking is to enable the deployment of cost effective direct drive HTS generators for large off-shore wind turbines. The improved conductor performance allows for a significant reduction of the length of HTS tapes required to generate the excitation field and thus to a reduction of the overall generator cost. This paper presents design and optimization work to find the best generator topology based on the 4X conductor to minimize the levelized cost of energy. The electromagnetic model uses the commercial package FlexPDE as the Finite Element Analysis (FEA) solver. The model takes the power and RPM requirements as inputs, and outputs the Levelized Cost of Energy (LCOE) for the turbine. The model estimates the actual mass and cost of the generator assuming mass production of multiple units per year. The paper presents the model developed in detail as well as the results obtained from the analysis through Monte-Carlo design space exploration. © 2002-2011 IEEE. Source


Chen T.-H.,University of Houston | Popov I.,University of Houston | Kaveevivitchai W.,University of Houston | Chuang Y.-C.,National Synchrotron Radiation Research Center | And 4 more authors.
Angewandte Chemie - International Edition | Year: 2015

Two mesoporous fluorinated metal-organic frameworks (MOFs) were synthesized from extensively fluorinated tritopic carboxylate- and tetrazolate-based ligands. The tetrazolate-based framework MOFF-5 has an accessible surface area of 2445m2 g-1, the highest among fluorinated MOFs. Crystals of MOFF-5 adsorb hydrocarbons, fluorocarbons, and chlorofluorocarbons (CFCs) - the latter two being ozone-depleting substances and potent greenhouse species - with weight capacities of up to 225 %. The material exhibits an apparent preference for the adsorption of non-spherical molecules, binding unusually low amounts of both tetrafluoromethane and sulfur hexafluoride. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Chen T.-H.,University of Houston | Kaveevivitchai W.,University of Houston | Jacobson A.J.,University of Houston | Jacobson A.J.,Texas Center for Superconductivity | Miljanic O.S.,University of Houston
Chemical Communications | Year: 2015

Commonly used inhalation anesthetics - enflurane, isoflurane, sevoflurane, halothane, and methoxyflurane - are adsorbed within the pores of a porous fluorinated molecular crystal to the tune of up to 73.4(±0.2)% by weight. Uptake of all studied anesthetics is quite fast, typically reaching saturation in less than three minutes. This journal is © The Royal Society of Chemistry. Source

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