@article{mcclure_oldham_walls_parsons_2013, title={Large effect of titanium precursor on surface reactivity and mechanical strength of electrospun nanofibers coated with TiO2 by atomic layer deposition}, volume={31}, ISSN={["0734-2101"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000327253900031&KeyUID=WOS:000327253900031}, DOI={10.1116/1.4817718}, abstractNote={Encapsulating and functionalizing polymer nanofibers can improve the polymers chemical resistance and surface reactivity, enabling new applications including biosensing, flexible electronics, gas filtration, and chemical separations. Polymer fiber functionalization typically involves energy intensive wet chemical treatments and/or plasma exposure. Recent results show low temperature atomic layer deposition (ALD) to be a viable means to coat nanofibers with uniform and conformal inorganic and hybrid organic–inorganic layers. For this article, the authors describe how the mechanical properties of nylon-6 nanofibers are affected by ALD coatings of TiO2 and other metal oxides. They find that the stress–strain behavior of nylon-6 nanofibers depends strongly on the specific precursor chemistry used in the coating process. For ALD TiO2 coatings, titanium tetrachloride tended to embrittle the fibers, whereas titanium isopropoxide had a more subtle effect. Physical characterization shows that the TiCl4 diffused into the nylon-6 and reacted subsurface, whereas the titanium isopropoxide tended to react on the surface producing a more abrupt organic/inorganic interface. Results show that precursor choice is an important factor when designing thin film coating processes on polymeric substrates.}, number={6}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={McClure, Christina D. and Oldham, Christopher J. and Walls, Howard J. and Parsons, Gregory N.}, year={2013} }
 @article{walls_riley_fedkiw_spontak_baker_khan_2003, title={Composite electrolytes from self-assembled colloidal networks}, volume={48}, ISSN={["0013-4686"]}, DOI={10.1016/S0013-4686(03)00187-7}, abstractNote={In this study, we present two approaches to developing composite electrolytes exploiting the self-assembling nature of colloidal fillers. The first system comprises of oligomers of poly(ethylene glycol) dimethyl ether, branched fumed silica particulates and lithium salt. The fumed silica forms a three-dimensional, self-supporting network that provides mechanical stability. The large pores of the network has little effect on diffusivity of ions and oligomers, lithium transference number and ionic conductivity, with the latter showing values >10−3 S/cm at ambient conditions. The second system consists of Li exchanged hectorite clay in a mixture of low molar mass carbonates. Similar to the fumed silica, the clay provides mechanical stability through formation of a three-dimensional network. In addition, the immobile clay platelets also serve as the anion rendering the system to be a single ion conductor. Near-unity transference number is observed in this case. However, the room temperature conductivity of the clay composite is lower than the fumed silica, revealing a value of about 10−4 S/cm. The lower conductivity can be attributed to the clay not being in a fully exfoliated form as evident from morphological analysis.}, number={14-16}, journal={ELECTROCHIMICA ACTA}, author={Walls, HJ and Riley, MW and Fedkiw, PS and Spontak, RJ and Baker, GL and Khan, SA}, year={2003}, month={Jun}, pages={2071–2077} }
 @article{walls_fedkiw_zawodzinski_khan_2003, title={Ion transport in silica nanocomposite electrolytes}, volume={150}, ISSN={["1945-7111"]}, DOI={10.1149/1.1544635}, abstractNote={The ion-transport properties of composite electrolytes composed of oligomers of poly(ethylene glycol) dimethyl ether, hydrophobic fumed silica, and Li(CF 3 SO 2 ) 2 N (LiTFSI) are investigated using nuclear magnetic resonance (NMR), electrophoretic NMR (ENMR), ac impedance spectroscopy, and rheology. The effects of fumed silica and salt concentration on ionic conductivity, diffusivity of ions and oligomers, and lithium transference number (T) are examined at 30°C. The fumed silica forms a self-supporting network with large pores such that the network, regardless of silica concentration, has little effect on ion-transport characteristics. Examination of the effect of salt on ion transport reveals a maximum ionic conductivity at around 1.06 M, which is attributed to a tradeoff of adding more charge carriers balanced against increased ion-ion interactions and reduced mobilities. T 1,i with respect to salt concentration surprisingly passes through a minimum around 0.35 M. The increase in T at higher concentrations is attributed to the mobilities of cations, anions, and solvating oligomer becoming constrained to the same value due to loss of free volume. The values of T Li at low salt concentrations (<0.35 M) are attributed to the ions existing in either a fully dissociated state or primarily as charged complexes. Results of T Li from ENMR and from estimation via pulse field gradient NMR (pfg-NMR) are compared showing that pfg-NMR consistently overestimates T Li . Finally, a comparison is presented of measured conductivity with that calculated from the Nernst-Einstein equation and diffusivities found from pfg-NMR measurement: we discuss possible reasons why it is inappropriate to estimate ion-pair formation by this comparison.}, number={3}, journal={JOURNAL OF THE ELECTROCHEMICAL SOCIETY}, author={Walls, HJ and Fedkiw, PS and Zawodzinski, TA and Khan, SA}, year={2003}, month={Mar}, pages={E165–E174} }
 @article{walls_riley_singhal_spontak_fedkiw_khan_2003, title={Nanocomposite electrolytes with fumed silica and hectorite clay networks: Passive versus active fillers}, volume={13}, ISSN={["1616-301X"]}, DOI={10.1002/adfm.200304333}, abstractNote={Abstract}, number={9}, journal={ADVANCED FUNCTIONAL MATERIALS}, author={Walls, HJ and Riley, MW and Singhal, RR and Spontak, RJ and Fedkiw, PS and Khan, SA}, year={2003}, month={Sep}, pages={710–717} }
 @article{walls_caines_sanchez_khan_2003, title={Yield stress and wall slip phenomena in colloidal silica gels}, volume={47}, number={4}, journal={Journal of Rheology (New York, N.Y.)}, author={Walls, H. J. and Caines, S. B. and Sanchez, A. M. and Khan, S. A.}, year={2003}, month={Jul}, pages={847–868} }
 @article{walls_zawodzinski_2000, title={Anion and cation transference numbers determined by electrophoretic NMR of polymer electrolytes sum to unity}, volume={3}, number={7}, journal={Electrochemical and Solid State Letters}, author={Walls, H. J. and Zawodzinski, T. A.}, year={2000}, pages={321–324} }
 @article{walls_zhou_yerian_fedkiw_khan_stowe_baker_2000, title={Fumed silica-based composite polymer electrolytes: synthesis, rheology, and electrochemistry}, volume={89}, ISSN={["0378-7753"]}, DOI={10.1016/S0378-7753(00)00424-9}, abstractNote={An overview of our research is presented on developing composite polymer electrolytes (CPEs) based on low-molecular weight polyethylene oxide (PEO) (namely, poly(ethylene glycol) dimethyl ether), lithium salts (e.g. lithium triflate, lithium imide, etc.), and fumed silica. These CPEs demonstrate high room-temperature conductivites (>10−3 S/cm), mechanical strength, and form stable interfaces with lithium metal as a result of the fumed silica. The surface groups on the fumed silica determine the mechanical properties of the CPE while the low-molecular weight PEO and lithium salt determine the ionic transport properties. These CPEs show promise as electrolytes for the next generation of rechargeable lithium batteries.}, number={2}, journal={JOURNAL OF POWER SOURCES}, author={Walls, HJ and Zhou, J and Yerian, JA and Fedkiw, PS and Khan, SA and Stowe, MK and Baker, GL}, year={2000}, month={Aug}, pages={156–162} }
 @article{raghavan_walls_khan_2000, title={Rheology of silica dispersions in organic liquids: New evidence for solvation forces dictated by hydrogen bonding}, volume={16}, ISSN={["0743-7463"]}, DOI={10.1021/la991548q}, abstractNote={Dispersions of hydrophilic fumed silica are investigated in a range of polar organic media. The silica forms stable, low-viscosity sols exhibiting shear thickening behavior in a host of liquids, including ethylene glycol and its oligomers and short-chain alcohols, such as n-propanol. In contrast, the silica flocculates into colloidal gels in other liquids, such as glycols with methyl end-caps and longer-chain alcohols. We suggest that there is a causal relationship between the hydrogen-bonding ability of the liquid and the colloidal microstructure observed. In strongly hydrogen-bonding liquids, a solvation layer is envisioned to form on the silica surface through hydrogen bonding between liquid molecules and surface silanol groups (Si−OH). This gives rise to short-range, non-DLVO repulsions (“solvation forces”) which stabilize the silica particles. In contrast, in the case of liquids with limited hydrogen-bonding ability, silanols on adjacent silica particles are envisioned to interact directly by hydroge...}, number={21}, journal={LANGMUIR}, author={Raghavan, SR and Walls, HJ and Khan, SA}, year={2000}, month={Oct}, pages={7920–7930} }
 @article{goldman_breitschwerdt_grindem_hegarty_walls_dumler_1998, title={Granulocytic Ehrlichiosis in Dogs from North Carolina and Virginia}, volume={12}, ISSN={0891-6640 1939-1676}, url={http://dx.doi.org/10.1111/j.1939-1676.1998.tb02096.x}, DOI={10.1111/j.1939-1676.1998.tb02096.x}, abstractNote={Medical records of 3 dogs from North Carolina and 3 dogs from Virginia with ehrlichial morulae in circulating neutrophils were studied retrospectively. Two clinically distinct disease syndromes, including chronic, moderate to severe anemia (n = 3) and polyarthritis (n = 2) were associated with canine granulocytic ehrlichiosis (CGE) in these dogs. One dog was clinically healthy, and abnormalities were not detected during physical examination. Clinical signs were nonspecific and included fever, lethargy, anorexia, vomiting, and diarrhea. The most frequent laboratory abnormalities were normocytic normochromic nonregenerative anemia, moderate thrombocytopenia with large platelets, lymphopenia, and eosinopenia. Considerable variability was found in the serologic responses toEhrlichia equi, Ehrlichia canis, andEhrlichia chaffeensisantigens among the 5 dogs for which stored sera were available for indirect fluorescent antibody testing. Polymerase chain reaction amplification and sequencing of portions of the 16S rRNA gene from blood (collected in ethylenediaminetetraacetic acid) of 1 severely anemic dog (dog 3) and 1 polyarthritic dog (dog 4) resulted in DNA sequences nearly identical to the GenBank accessions forEhrlichia ewingii.The DNA sequence from a 3rd dog (dog 5) was most similar to that ofE. canis.Serologic or molecular results support the possibility ofE. ewingii, E. equi, andE. caniscoinfection or serologic cross‐reactivity among canine granulocytic and monocyticEhrlichiaspecies in dogs from North Carolina and Virginia. Variability in response to tetracycline or doxycycline treatment was noted in these dogs, with more rapid resolution of signs in dogs with polyarthritis. We report the 1st cases of CGE in dogs from North Carolina and Virginia, including recognition of CGE in a healthy dog.}, number={2}, journal={Journal of Veterinary Internal Medicine}, publisher={Wiley}, author={Goldman, Elizabeth E. and Breitschwerdt, Edward B. and Grindem, Carol B. and Hegarty, Barbara C. and Walls, Jennifer J. and Dumler, J. Stephen}, year={1998}, month={Mar}, pages={61–70} }