Kenneth J. Klabunde

Reactive magnesium oxide nanoparticles and halogen (Cl2, Br2) adducts of these MgO particles were allowed to contact certain bacteria and spore cells. Bacteriological test data, atomic force microscopy (AFM) images, and electron microscopy (TEM) images are provided, which yield insight into the biocidal action of these nanoscale materials. The tests show that these materials are very effective against Gram-positive and Gram-negative bacteria as well as spores. ζ-Potential measurements show an attractive interaction between the MgO nanoparticles and bacteria and spore cells, which is confirmed by confocal microscopy images. The AFM studies illustrate considerable changes in the cell membranes upon treatment, resulting in the death of the cells. TEM micrographs confirm these results and supply additional information about the processes inside the cells. Overall, the results presented illustrate that dry powder nanoparticulate formulations as well as water slurries are effective. It is proposed that abrasiveness, basic character, electrostatic attraction, and oxidizing power (due to the presence of active halogen) combine to promote these biocidal properties.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTXPS studies of solvated metal atom dispersed (SMAD) catalysts. Evidence for layered cobalt-manganese particles on alumina and silicaBeng Jit Tan, Kenneth J. Klabunde, and Peter M. A. SherwoodCite this: J. Am. Chem. Soc. 1991, 113, 3, 855–861Publication Date (Print):January 1, 1991Publication History Published online1 May 2002Published inissue 1 January 1991https://pubs.acs.org/doi/10.1021/ja00003a019https://doi.org/10.1021/ja00003a019research-articleACS PublicationsRequest reuse permissionsArticle Views6463Altmetric-Citations913LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Nanocrystals of MgO and CaO have been prepared by a modified aerogel/hypercritical drying/dehydration method. For nanocrystalline MgO (AP-MgO) surface areas ranged from 250 to 500 m2/g, whereas for AP-CaO 100−160 m2/g. These materials have been compared with more conventional (CP) microcrystalline samples of lower surface area with regard to (1) morphology (AP-samples (autoclave preparation) are tiny polyhedral crystallites, while CP-samples (conventional preparation) are larger, hexagonal platelets and cubes); (2) residual surface OH (AP-samples have less acidic OH, which are more isolated from each other; (3) acid gas adsorption (AP-samples adsorb more SO2 and CO2 at low pressures and room temperature and prefer monodentate rather than bidentate adsorption modes, but at higher pressures CP-samples adsorb more SO2 and HCl apparently due to the formation of more well ordered multilayers); (4) destructive adsorption of organophosphorus compounds and chlorocarbons (AP-samples are superior due to higher surface areas and higher surface reactivities), and (5) very thin layers of transition metal oxides on the MgO and CaO nanocrystals that significantly enhance destructive adsorption capacities to the point where [MxOy]AP-MgO and [MxOy]AP-CaO become stoichiometric in reaction with CCl4. The data are conclusive that the nanocrystals are more reactive than the microcrystals, and this is mainly attributed to morphological differences, including defects. However, intrinsic electronic effects due purely to “smallness” cannot be ruled out.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTX-ray photoelectron spectroscopy studies of solvated metal atom dispersed catalysts. Monometallic iron and bimetallic iron-cobalt particles on aluminaBeng Jit Tan, Kenneth J. Klabunde, and Peter M. A. SherwoodCite this: Chem. Mater. 1990, 2, 2, 186–191Publication Date (Print):March 1, 1990Publication History Published online1 May 2002Published inissue 1 March 1990https://pubs.acs.org/doi/10.1021/cm00008a021https://doi.org/10.1021/cm00008a021research-articleACS PublicationsRequest reuse permissionsArticle Views2082Altmetric-Citations422LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

The room-temperature reactions of the chemical warfare agents VX (O-ethyl S-2-(diisopropylamino)ethyl methylphosphonothioate), GD (3,3-dimethyl-2-butyl methylphosphonofluoridate, or Soman), and HD (2,2‘-dichloroethyl sulfide, or mustard) with nanosize MgO have been studied using solid-state MAS NMR. All three agents hydrolyze on the surface of the very reactive MgO nanoparticles. VX yields ethyl methylphosphonic acid (EMPA) and methylphosphonic acid (MPA), but no toxic S-(2-diisopropylamino)ethyl methylphosphonothioate (EA-2192). GD forms both GD-acid and MPA. For HD, in addition to hydrolysis to thiodiglycol, about 50% elimination to divinyl sulfide occurs. The reaction kinetics for all three agents are characterized by a fast initial reaction followed by gradual slowing to a steady-state reaction with first-order behavior. The fast reaction is consistent with liquid spreading through the porous nanoparticle aggregates. The steady-state reaction is identified as a gas-phase reaction, mediated by evaporation, once the liquid achieves its volume in the smallest available pores.