Joan E Curry

Interests

No activities entered.

Courses

Scholarly Contributions

Chapters

• Curry, J. E. (2016). Poisson-Boltzmann Equation. In Encyclopedia of Geochemistry(pp pp 1-2). Springer-International Publishing. doi:10.1007

Journals/Publications

• Curry, J. E. (2021). A close look at change: the role of an instructional-team community on an Instructor's evolution during instructional reform. Disciplinary and Interdisciplinary Science Education Research, 3, 8-26.
• Southard, K. M., Hester, S. D., Jurkiewicz, J., Curry, J. E., Kim, Y. A., Cox, J., Elfring, L. K., Blowers, P., & Talanquer, V. (2021). A close look at change: the role of an instructional-team community on an Instructor’s evolution during instructional reform. Disciplinary and Interdisciplinary Science Education Research, 3(Issue 1). doi:10.1186/s43031-021-00036-9
  More info

  In transforming undergraduate STEM education, it is important to understand the personal and contextual factors that impact instructors’ reform efforts. In this study we explored an instructor’s drivers and motivators for change in perspectives and practice, with an emphasis on the impact of an internal community (her ‘instructional team’) comprised of a co-instructor, graduate teaching assistants, and several undergraduate learning assistants (LAs). Data were collected over two semesters through classroom observations, interviews, faculty learning community discussion recordings, and team email communications. We identified pedagogical discontentment as a primary initial trigger for the instructor’s engagement in instructional reform, guided by personal values and beliefs about student learning and the nature of her discipline. The instructional-team community, which was established during a period of instructional distress, provided 1) consistent support in instructional planning, implementation, assessment, and reflection processes, 2) unique access to different perspectives on the nuances of the teaching environment and student challenges, 3) increased space, time, and motivation for the instructor to more critically reflect on her teaching and engage in creative instructional design. This case illustrates the potential effects of instructional team-based communities on instructors as they work to improve their practice and reform their courses.
• Talanquer, V. A., Blowers, P., Elfring, L. K., Cox, J. T., Kim, Y. A., Curry, J. E., Jurkiewicz, J., Hester, S. D., & Southard, K. M. (2021). A close look at change: the role of community on an instructor's evolution during instructional reform. Disciplinary and Interdisciplinary Science Education Research.
• Hogan, D. E., Tian, F., Malm, S. W., Olivares, C., Pacheco, R. P., Simonich, M. T., Hunjan, A. S., Tanguay, R. L., Klimecki, W. T., Polt, R., Pemberton, J. E., Curry, J. E., & Maier, R. M. (2019). Biodegradability and toxicity of monorhamnolipid biosurfactant diastereomers. JOURNAL OF HAZARDOUS MATERIALS, 364, 600-607.
• Hogan, D. E., Tian, F., Malm, S. W., Olivares, C., Palos Pacheco, R., Simonich, M. T., Hunjan, A. S., Tanguay, R. L., Klimecki, W. T., Polt, R., Pemberton, J. E., Curry, J. E., & Maier, R. M. (2019). Biodegradability and toxicity of monorhamnolipid biosurfactant diastereomers. Journal of Hazardous Materials, 364(Issue). doi:10.1016/j.jhazmat.2018.10.050
  More info

  Synthetic monorhamnolipids differ from biologically produced material because they are produced as single congeners, depending on the β-hydroxyalkanoic acid used during synthesis. Each congener is produced as one of four possible diastereomers resulting from two chiral centers at the carbinols of the lipid tails [(R,R), (R,S), (S,R) and (S,S)]. We compare the biodegradability (CO2 respirometry), acute toxicity (Microtox assay), embryo toxicity (Zebrafish assay), and cytotoxicity (xCELLigence and MTS assays) of synthetic rhamnosyl-β-hydroxydecanoyl-β-hydroxydecanoate (Rha-C10-C10) monorhamnolipids against biosynthesized monorhamnolipid mixtures (bio-mRL). All Rha-C10-C10 diastereomers and bio-mRL were inherently biodegradable ranging from 34 to 92% mineralized. The Microtox assay showed all Rha-C10-C10 diastereomers and bio-mRL are slightly toxic according to the US EPA ecotoxicity categories with 5 min EC50 values ranging from 39.6 to 87.5 μM. The zebrafish assay showed that of 22 developmental endpoints tested, only mortality was observed at 120 h post fertilization; all Rha-C10-C10 diastereomers and bio-mRL caused significant mortality at 640 μM, except the Rha-C10-C10 (R,R) which showed no developmental effects. xCELLigence and MTS showed IC50 values ranging from 103.4 to 191.1 μM for human lung cell line H1299 after 72 h exposure. These data provide key information regarding Rha-C10-C10 diastereomers that is pertinent when considering potential applications.
• Maier, R. M., Curry, J. E., Pemberton, J. E., Polt, R. L., Klimecki, W., Tanguay, R. L., Hunjan, A. S., Simonich, M., Palos Pacheco, R., Olivares, C., Malm, S. W., Tian, F., & Hogan, D. E. (2019). Biodegradability and toxicity of monorhamnolipid biosurfactant diastereomers. Journal of Hazardous Materials, 364, 600-607. doi:10.1016/j.jhazmat.2018.10.050
• Hogan, D. E., Curry, J. E., & Maier, R. M. (2018). Ion Flotation of La3+, Cd2+ and Cs+ using monorhamnolipid collector. Colloids and Interfaces, 2(4), 43. doi:10.3390
• Hogan, D. E., Curry, J. E., & Maier, R. M. (2018). Ion flotation of la3+, cd2+, and cs+ using monorhamnolipid collector. Colloids and Interfaces, 2(Issue 4). doi:10.3390/colloids2040043
  More info

  Water scarcity is a global issue that is expected to continue increasing in importance in the coming decades. Reclaimed water is one important source available to meet future needs. The reclamation process for wastewaters, particularly from industrial sources, involves the need to remove low-level contaminants. Here we report the efficacy of an ion flotation process that uses the biosurfactant monorhamnolipid as a metal collector to recover Cs+, Cd2+, and La3+ from water. These elements were tested at collector-to-colligend ratios of 2, 5, and 10. The collector-to-colligend ratio and metal valence play a large role in determining flotation success with removal efficiencies varying widely. The maximum removal efficiency for the metals when floated individually were 46.2, 99.8, and 98.6% for Cs+, Cd2+, and La3+, respectively. When mixed together at near equimolar concentrations removal efficiencies were 39.4, 98.4, and 88.1%, respectively. Removal efficiency for Cs+, Cd2+, and La3+ were up to 49.9, 99.5, and 51.5% when mixed at a ratio of 200:10:1, whereas conditional stability constants predict a removal order of La3+ > Cd2+ > Cs+ . Future research should examine parameters, including pH and ionic strength, that may affect the flotation process as well as actual metal-contaminated waste streams to evaluate the usefulness of this technology.
• Maier, R. M., Curry, J. E., & Hogan, D. E. (2018). Ion Flotation of La3+, Cd2+, and Cs+ using Monorhamnolipid Collector. Colloids and Interfaces, 2(43). doi:10.3390/colloids2040043
• Maier, R. M., Curry, J. E., & Hogan, D. E. (2018). Ion flotation of La3+, Cd2+, and Cs+ using monorhamnolipid collector.. Colloids Interfaces, 2(4), 43-58. doi:10.3390/colloids2040043
• Hogan, D. E., Curry, J. E., Pemberton, J. E., & Maier, R. M. (2017). Rhamnolipid biosurfactant complexation of rare earth elements. JOURNAL OF HAZARDOUS MATERIALS, 340, 171-178.
• Hogan, D. E., Curry, J. E., Pemberton, J. E., & Maier, R. M. (2017). Rhamnolipid biosurfactant complexation of rare earth elements. Journal of Hazardous Materials, 340(Issue). doi:10.1016/j.jhazmat.2017.06.056
  More info

  Rare earth elements (REE) are vital for modern technologies and considered critical materials. This study investigated monorhamnolipid biosurfactant interactions with REE as the basis for REE recovery technology. Conditional stability constants (log β), measured using a resin-based ion exchange method, are reported for 16 REE and metals. These results were combined with existing data for 10 other metals to assess comparative strength and determinants of binding. The stability constants could be divided into three groups: weakly, moderately, and strongly bound. The REE were all in the strongly bound group (UO2 2+, Eu3+, Nd3+, Tb3+, Dy3+, La3+, Cu2+, Al3+, Pb2+, Y3+, Pr3+, and Lu3+) with log β ranging from 9.82 to 8.20. The elements Cd2+, In3+, Zn2+, Fe3+, Hg2+, and Ca2+ were moderately bound with log β = 7.17–4.10. Finally, Sr2+, Co2+, Ni2+, UO2 2+, Ba2+, Mn2+, Mg2+, Rb+, and K+ were weakly bound with log β = 3.95–0.96. Two log β values are reported for the uranyl ion due to two distinct binding regions. A mixed metals study and associated selectivity coefficients confirmed monorhamnolipids preferentially remove metals with large log β values over those with smaller values. Preferential complexation by monorhamnolipids may constitute a green pathway for recovery of REE from alternative, non-traditional sources.
• Curry, J. E., & Kim, S. (2014). Adhesion: Coated Surface, Effects of Humidity. Dekker Encyclopedia of Nanoscience and Nanotechnology, Third Edition.
• Matthieu, D. E., Brusseau, M. L., Johnson, G. R., Artiola, J. L., Bowden, M. L., & Curry, J. E. (2013). Intercalation of trichloroethene by sediment-associated clay minerals. Chemosphere, 90(Issue 2). doi:10.1016/j.chemosphere.2012.07.061
  More info

  The objective of this research was to examine the potential for intercalation of trichloroethene (TCE) by clay minerals associated with aquifer sediments. Sediment samples were collected from a field site in Tucson, AZ. Two widely used Montmorillonite specimen clays were employed as controls. X-ray diffraction, conducted with a controlled-environment chamber, was used to characterize smectite interlayer d-spacing for three treatments (bulk air-dry sample, sample mixed with synthetic groundwater, sample mixed with TCE-saturated synthetic groundwater). The results show that the d-spacing measured for the samples treated with TCE-saturated synthetic groundwater are larger (∼26%) than those of the untreated samples for all field samples as well as the specimen clays. These results indicate that TCE was intercalated by the clay minerals, which may have contributed to the extensive elution tailing observed in prior miscible-displacement experiments conducted with this sediment. © 2012 Elsevier Ltd.
• Matthieu, I. D., Brusseau, M., Johnson, G., Artiola, J., Bowden, M., & Curry, J. (2013). Intercalation of trichloroethene by sediment associated clay minerals. Chemosphere, 90, 459-463.
• Baughman, K. F., Curry, J. E., & Maier, R. M. (2010). Evaporative Deposition of Bacteria from a Sessile Drop: Effects of Suspension Aging. MRS Proceedings, 1273(1), 30401-30406. doi:10.1557/proc-1273-mm03-04
  More info

  In this work, we report on the evaporative deposition of bacteria from a drying aqueous drop on mica as a function of the bacterial suspension age. For sufficiently aged bacterial suspensions, residues are small and more filled-in than residues formed from fresh suspensions on similarly aged mica. In addition, the interior deposition pattern transitions from a cellular film characteristic of fresh suspensions to a cracked carpet pattern for aged suspensions. Suspension aging related changes in the residues are attributed to accumulation of organic materials such as DNA, RNA, proteins, and other bacterial components in the suspension. The aging process is also observed to be at least partially dependent on ventilation of the suspension during aging.
• Baughman, K. F., Curry, J. E., Maier, R. M., & Norris, T. A. (2010). Evaporative Deposition of Bacteria and Microspheres on Mica from a Sessile Drop: The Use of Surface Conditioning in a Laboratory Atmosphere to Control Drop Spreading and Particle Deposition Patterns. MRS Proceedings, 1273(1), 30301-30306. doi:10.1557/proc-1273-mm03-03
  More info

  Evaporative deposition from a sessile drop is an appealing way to deposit materials on a surface due to the simplicity of the technique. In this work we deposit aqueous solutions of two types of colloidal particles, namely bacteria and microspheres, on mica. We show that by controlling the extent of initial drop spreading through subtle changes in surface conditioning caused by exposure to the laboratory atmosphere in a laminar flow hood it is possible to systematically vary the particle deposition patterns. On freshly cleaved mica the contact angle of water is < 5°. Drops of bacterial and microsphere solutions deposited on freshly cleaved mica spread to cover a large surface area. Drying occurs through pinning and depinning events leaving a series of colloidal particle rings. We found in our laboratory that the contact angle of water on mica exposed to a constant flow of filtered laboratory air in a laminar flow hood gradually increases with time. For drops of both bacterial and microsphere solutions there is a corresponding decrease in the extent of drop spreading with increasing exposure of the mica surface to laboratory air. This results in a profound change in the colloidal particle deposition pattern. Short exposures of minutes to hours are enough to decrease spreading and affect the resulting deposition pattern. For our longest mica surface exposure times (months to 1 year) the contact angle of water reaches values near 20°. Spreading of the bacterial and microsphere drops is substantially decreased. A portion of the colloidal particles are deposited in an outer deposition ring which marks the extent of drop spreading and the remainder of the particles are deposited in the drop interior as a honeycomb or cellular film. The fraction of the drop residue covered with the cellular film increases with particle concentration as well as the length of time the mica is exposed to the laboratory atmosphere. This work shows that evaporative deposition on mica is very sensitive to surface conditioning through atmospheric exposure and also suggests that particle deposition patterns can be tuned by small changes in drop spreading.
• Baughman, K. F., Maier, R. M., Norris, T. A., Beam, B. M., Mudalige, A., Pemberton, J. E., & Curry, J. E. (2010). Evaporative deposition patterns of bacteria from a sessile drop: Effect of changes in surface wettability due to exposure to a laboratory atmosphere. Langmuir, 26(Issue 10). doi:10.1021/la100932k
  More info

  Evaporative deposition from a sessile drop is a simple and appealing way to deposit materials on a surface. In this work, we deposit living, motile colloidal particles (bacteria) on mica from drops of aqueous solution. We show for the first time that it is possible to produce a continuous variation in the deposition pattern from ring deposits to cellular pattern deposits by incremental changes in surface wettability which we achieve by timed exposure of the mica surface to the atmosphere. We show that it is possible to change the contact angle of the drop from less than 5° to near 20° by choice of atmospheric exposure time. This controls the extent of drop spreading, which in turn determines the architecture of the deposition pattern. © 2010 American Chemical Society.
• Curry, J., Baughman, K. F., Maier, R. M., Norris, T. A., Beam, B. M., Mudalige, A., Pemberton, J. E., & Curry, J. E. (2010). Evaporative deposition patterns of bacteria from a sessile drop: effect of changes in surface wettability due to exposure to a laboratory atmosphere. Langmuir : the ACS journal of surfaces and colloids, 26(10).
  More info

  Evaporative deposition from a sessile drop is a simple and appealing way to deposit materials on a surface. In this work, we deposit living, motile colloidal particles (bacteria) on mica from drops of aqueous solution. We show for the first time that it is possible to produce a continuous variation in the deposition pattern from ring deposits to cellular pattern deposits by incremental changes in surface wettability which we achieve by timed exposure of the mica surface to the atmosphere. We show that it is possible to change the contact angle of the drop from less than 5 degrees to near 20 degrees by choice of atmospheric exposure time. This controls the extent of drop spreading, which in turn determines the architecture of the deposition pattern.
• Chaves, L. H., Curry, J. E., Stone, D. A., Carducci, M. D., & Chorover, J. (2009). Nickel incorporation in FE(II, III) hydroxysulfate green Rust: Effect on crystal lattice spacing and oxidation products. Revista Brasileira de Ciencia do Solo, 33(Issue 5). doi:10.1590/s0100-06832009000500005
  More info

  Ni(II)-Fe(II)-Fe(III) layered double hydroxides (LDH) or Ni-containing sulfate green rust (GR2) samples were prepared from Ni(II), Fe(II) and Fe(III) sulfate salts and analyzed with X ray diffraction. Nickel is readily incorporated in the GR2 structure and forms a solid solution between GR2 and a Ni(II)-Fe(III) LDH. There is a correlation between the unit cell a-value and the fraction of Ni(II) incorporated into the Ni(II)-GR2 structure. Since there is strong evidence that the divalent/trivalent cation ratio in GR2 is fixed at 2, it is possible in principle to determine the extent of divalent cation substitution for Fe(II) in GR2 from the unit cell a-value. Oxidation forms a mixture of minerals but the LDH structure is retained if at least 20 % of the divalent cations in the initial solution are Ni(II). It appears that Ni(II) is incorporated in a stable LDH structure. This may be important for two reasons, first for understanding the formation of LDHs, which are anion exchangers, in the natural environment. Secondly, this is important for understanding the fate of transition metals in the environment, particularly in the presence of reduced Fe compounds.
• Helena, L., Curry, J. E., Stone, D. A., Carducci, M. D., & Chorover, J. (2009). Nickel incorporation in FE(II, III) hydroxysulfate green Rust: Effect on crystal lattice spacing and oxidation products. Revista Brasileira de Ciencia do Solo, 33(5), 1115-1123.
  More info

  Abstract: Ni(II)-Fe(II)-Fe(III) layered double hydroxides (LDH) or Ni-containing sulfate green rust (GR2) samples were prepared from Ni(II), Fe(II) and Fe(III) sulfate salts and analyzed with X ray diffraction. Nickel is readily incorporated in the GR2 structure and forms a solid solution between GR2 and a Ni(II)-Fe(III) LDH. There is a correlation between the unit cell a-value and the fraction of Ni(II) incorporated into the Ni(II)-GR2 structure. Since there is strong evidence that the divalent/trivalent cation ratio in GR2 is fixed at 2, it is possible in principle to determine the extent of divalent cation substitution for Fe(II) in GR2 from the unit cell a-value. Oxidation forms a mixture of minerals but the LDH structure is retained if at least 20 % of the divalent cations in the initial solution are Ni(II). It appears that Ni(II) is incorporated in a stable LDH structure. This may be important for two reasons, first for understanding the formation of LDHs, which are anion exchangers, in the natural environment. Secondly, this is important for understanding the fate of transition metals in the environment, particularly in the presence of reduced Fe compounds.
• Brown, T., Chang, C., Heinze, B., Hollinger, P., Kittleson, J., MacDow, K., Reavis, D., Curry, J., & Riley, M. (2007). Development of an inducible three colour bacterial water colour system. IET Synthetic Biology, 1(1-2), 21-24.
  More info

  Abstract: Here we present the work of the 2006 University of Arizona team in the iGEM (international Genetically Engineered Machine) competition sponsored by MIT. Our aim was to develop an inducible water colour system for painting bacteria in three colours. Using BioBricks, a plasmid was designed for insertion into E. coli which would allow the bacterium to respond to each of three different chemical inducers by producing yellow, cyan or red fluorescent proteins. In principle the inducers could be deposited on a bacterial lawn using a high-resolution printer so that three colour images could be produced with a spatial resolution matching the size of the bacterium. This could be the first step towards producing a bacterial lawn that behaves like a canvas for watercolour painting or eventually a three-colour television set. The application connects with current interest in precise control of cellular response desired in biosensors and bioengineered materials. The University of Arizona iGEM team called the 'Cell Raisers' was assembled in May 2006 and worked enthusiastically throughout the summer. The team was comprised of six undergraduates (Tyler Brown, Brian Heinze, Patrick Hollinger, Josh Kittleson, Kevin MacDow, and Dan Reavis), one graduate student (Carlos Chang), and two faculty members (Joan Curry and Mark Riley). This proved to be an ambitious project, and while the final goal was not fully realised, first steps were made in terms of design, plasmid construction and bacterial deposition with an inkjet printer. Patrick Hollinger and Brian Heinze gave the technical presentation to judges and competing teams on Saturday, November 4, 2006 in MIT's Stata Center. The team also presented a poster that was viewed in the evening after all the presentations. For their efforts, the University of Arizona team received honourable mention with special consideration: 'For progress toward synthetic biology in three colours'. © 2007 The Institution of Engineering and Technology.
• Brown, T., Chang, C., Heinze, B., Hollinger, P., Kittleson, J., MacDow, K., Reavis, D., Curry, J., & Riley, M. (2007). Development of an inducible three colour bacterial water colour system. IET Synthetic Biology, 1(Issue 1-2). doi:10.1049/iet-stb:20070015
  More info

  Here we present the work of the 2006 University of Arizona team in the iGEM (international Genetically Engineered Machine) competition sponsored by MIT. Our aim was to develop an inducible water colour system for painting bacteria in three colours. Using BioBricks, a plasmid was designed for insertion into E. coli which would allow the bacterium to respond to each of three different chemical inducers by producing yellow, cyan or red fluorescent proteins. In principle the inducers could be deposited on a bacterial lawn using a high-resolution printer so that three colour images could be produced with a spatial resolution matching the size of the bacterium. This could be the first step towards producing a bacterial lawn that behaves like a canvas for watercolour painting or eventually a three-colour television set. The application connects with current interest in precise control of cellular response desired in biosensors and bioengineered materials. The University of Arizona iGEM team called the 'Cell Raisers' was assembled in May 2006 and worked enthusiastically throughout the summer. The team was comprised of six undergraduates (Tyler Brown, Brian Heinze, Patrick Hollinger, Josh Kittleson, Kevin MacDow, and Dan Reavis), one graduate student (Carlos Chang), and two faculty members (Joan Curry and Mark Riley). This proved to be an ambitious project, and while the final goal was not fully realised, first steps were made in terms of design, plasmid construction and bacterial deposition with an inkjet printer. Patrick Hollinger and Brian Heinze gave the technical presentation to judges and competing teams on Saturday, November 4, 2006 in MIT's Stata Center. The team also presented a poster that was viewed in the evening after all the presentations. For their efforts, the University of Arizona team received honourable mention with special consideration: 'For progress toward synthetic biology in three colours'. © 2007 The Institution of Engineering and Technology.
• Chaves, L. H., Curry, J. E., Stone, D. A., & Chorover, J. (2007). Fate of nickel ion in (II-III) hydroxysulphate green rust synthesized by precipitation and coprecipitation. Revista Brasileira de Ciencia do Solo, 31(Issue 4). doi:10.1590/s0100-06832007000400021
  More info

  In order to investigate the efficiency of sulfate green rust (GR2) to remove Ni from solution, GR2 samples were synthesized under controlled laboratory conditions. Some GR2 samples were synthesized from Fe(II) and Fe(III) sulfate salts by precipitation. Other samples were prepared by coprecipitation, of Ni(II), Fe(II) and Fe(III) sulfate salts, i.e., in the presence of Ni. In another sample, Ni(II) sulfate salt was added to pre-formed GR2. After an initial X-ray diffraction (XRD) characterization all samples were exposed to ambient air in order to understand the role of Ni in the transformation of the GR2 samples. XRD was repeated after 45 days. The results showed that Nious GR2 prepared by coprecipitation is isomorphous to Ni-free GR2, i.e. Ni is incorporated into the crystalline structure. Fe(II) was not replaced by Ni(II) in the crystalline structure of GR2 formed prior to exposure to solution-phase Ni. This suggests Ni was adsorbed to the GR2 surface. Sulfate green rust is more efficient in removing Ni from the environment by coprecipitation.
• Helena, L., Curry, J. E., Stone, D. A., & Chorover, J. (2007). Fate of nickel ion in (II-III) hydroxysulphate green rust synthesized by precipitation and coprecipitation. Revista Brasileira de Ciencia do Solo, 31(4), 813-818.
  More info

  Abstract: In order to investigate the efficiency of sulfate green rust (GR2) to remove Ni from solution, GR2 samples were synthesized under controlled laboratory conditions. Some GR2 samples were synthesized from Fe(II) and Fe(III) sulfate salts by precipitation. Other samples were prepared by coprecipitation, of Ni(II), Fe(II) and Fe(III) sulfate salts, i.e., in the presence of Ni. In another sample, Ni(II) sulfate salt was added to pre-formed GR2. After an initial X-ray diffraction (XRD) characterization all samples were exposed to ambient air in order to understand the role of Ni in the transformation of the GR2 samples. XRD was repeated after 45 days. The results showed that Nious GR2 prepared by coprecipitation is isomorphous to Ni-free GR2, i.e. Ni is incorporated into the crystalline structure. Fe(II) was not replaced by Ni(II) in the crystalline structure of GR2 formed prior to exposure to solution-phase Ni. This suggests Ni was adsorbed to the GR2 surface. Sulfate green rust is more efficient in removing Ni from the environment by coprecipitation.
• Curry, J. E., Heo, C. H., & Maier, R. M. (2006). COLL 77-Directly measuring the adhesive and elastic properties of bacteria using a Surface Force Apparatus. ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, 232.
• Curry, J. E., Tashvighi-Khoob, N., Baughman, K. F., Heo, C. H., Maier, R. M., & Goldstein, R. E. (2006). Evaporative deposition of bacteria on surfaces: Two dimensional films, cellular patterns and potential for constructing living functional materials. ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, 231.
• Heo, C. H., Maier, R. M., & Curry, J. E. (2006). Directly measuring the adhesive and elastic properties of bacteria using a Surface Force Apparatus: Effect of desiccation. ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, 231.
• Curry, J., Kim, S., Cho, K., & Curry, J. E. (2005). Measurements of the thickness compressibility of an n-octadecyltriethoxysilane monolayer self-assembled on mica. Langmuir : the ACS journal of surfaces and colloids, 21(18).
  More info

  The surface forces apparatus technique and the Johnson-Kendall-Roberts theory were used to study the elastic properties of an n-octadecyltriethoxysilane self-assembled monolayer (OTE-SAM) on both untreated and plasma-treated mica. Our aim was to measure the thickness compressibilities of OTE monolayers on untreated and plasma-treated mica and to estimate their surface densities and phase-states from the film compressibility. The compressibility moduli of OTE are (0.96 +/- 0.02) x 10(8) N/m(2) on untreated mica and (1.24 +/- 0.06) x 10(8) N/m(2) on plasma-treated mica. This work suggests that the OTE phase-state is pseudocrystalline. In addition, the results from the compressibility measurements in water vapor suggest that the OTE-SAM on both untreated and plasma-treated mica is not homogeneous but rather contains both crystalline polymerized OTE domains and somewhat hydrophilic gaseous regions.
• Kim, S., Cho, K., & Curry, J. E. (2005). Measurements of the thickness compressibility of an N- octadecyltriethoxysilane monolayer self-assembled on mica. Langmuir, 21(18), 8290-8296.
  More info

  PMID: 16114933;Abstract: The surface forces apparatus technique and the Johnson-Kendall-Roberts theory were used to study the elastic properties of an n- octadecyltriethoxysilane self-assembled monolayer (OTE-SAM) on both untreated and plasma-treated mica. Our aim was to measure the thickness compressibilities of OTE monolayers on untreated and plasma-treated mica and to estimate their surface densities and phase-states from the film compressibility. The compressibility moduli of OTE are (0.96 ± 0.02) × 10 8 N/m 2 on untreated mica and (1.24 ± 0.06) × 108 N/m 2 on plasma-treated mica. This work suggests that the OTE phase-state is pseudocrystalline. In addition, the results from the compressibility measurements in water vapor suggest that the OTE-SAM on both untreated and plasma-treated mica is not homogeneous but rather contains both crystalline polymerized OTE domains and somewhat hydrophilic gaseous regions. © 2005 American Chemical Society.
• Kim, S., Cho, K., & Curry, J. E. (2005). Measurements of the thickness compressibility of an N- octadecyltriethoxysilane monolayer self-assembled on mica. Langmuir, 21(Issue 18). doi:10.1021/la050689r
  More info

  The surface forces apparatus technique and the Johnson-Kendall-Roberts theory were used to study the elastic properties of an n- octadecyltriethoxysilane self-assembled monolayer (OTE-SAM) on both untreated and plasma-treated mica. Our aim was to measure the thickness compressibilities of OTE monolayers on untreated and plasma-treated mica and to estimate their surface densities and phase-states from the film compressibility. The compressibility moduli of OTE are (0.96 ± 0.02) × 10 8 N/m 2 on untreated mica and (1.24 ± 0.06) × 108 N/m 2 on plasma-treated mica. This work suggests that the OTE phase-state is pseudocrystalline. In addition, the results from the compressibility measurements in water vapor suggest that the OTE-SAM on both untreated and plasma-treated mica is not homogeneous but rather contains both crystalline polymerized OTE domains and somewhat hydrophilic gaseous regions. © 2005 American Chemical Society.
• Kim, S., Christenson, H. K., & Curry, J. E. (2003). n-Octadecyltriethoxysilane monolayer coated surfaces in humid atmospheres: Influence of capillary condensation on surface deformation and adhesion. Journal of Physical Chemistry B, 107(16), 3774-3781.
  More info

  Abstract: We have investigated the effect of humidity on surface deformation and adhesion of mica surfaces coated with n-octadecyltriethoxysilane self-assembled monolayers using a surface forces apparatus. The Maugis model of contact elasticity based on linear elastic fracture mechanics is used to analyze the results. The Laplace pressure is assumed to act in the "Dugdale" zone outside the contact area to account for capillary condensation. We measure the radius of the contact area as a function of applied load and use the model to obtain the surface energy and elastic constant of these surfaces for humidities ranging from 0 to 99%. The limiting values in dry and near-saturated conditions are as expected from well-known theories. A significant result is that we also obtain the surface energy for intermediate humidities. Increasing humidity modifies the deformed shape of the surfaces in contact due to capillary condensation. The sharp bifurcation at the edge of the contact zone for low humidities (JKR-type contact) is replaced by rounded edges (DMT-type contact) with increasing humidity. This is predicted by the Maugis model and is experimentally observed using optical interference fringes of equal chromatic order. We are able to separate the capillary condensation and solid-solid contributions to the adhesive force because the Maugis model allows a direct calculation of the area on which the Laplace pressure acts. At humidities approaching saturation the forces due to capillary condensation dominate monolayer-monolayer adhesion. At lower humidities both capillary condensation and direct monolayer-monolayer interaction contribute to the overall adhesion. © 2003 American Chemical Society.
• Kim, S., Christenson, H. K., & Curry, J. E. (2003). n-Octadecyltriethoxysilane monolayer coated surfaces in humid atmospheres: Influence of capillary condensation on surface deformation and adhesion. Journal of Physical Chemistry B, 107(Issue 16). doi:10.1021/jp0265992
  More info

  We have investigated the effect of humidity on surface deformation and adhesion of mica surfaces coated with n-octadecyltriethoxysilane self-assembled monolayers using a surface forces apparatus. The Maugis model of contact elasticity based on linear elastic fracture mechanics is used to analyze the results. The Laplace pressure is assumed to act in the "Dugdale" zone outside the contact area to account for capillary condensation. We measure the radius of the contact area as a function of applied load and use the model to obtain the surface energy and elastic constant of these surfaces for humidities ranging from 0 to 99%. The limiting values in dry and near-saturated conditions are as expected from well-known theories. A significant result is that we also obtain the surface energy for intermediate humidities. Increasing humidity modifies the deformed shape of the surfaces in contact due to capillary condensation. The sharp bifurcation at the edge of the contact zone for low humidities (JKR-type contact) is replaced by rounded edges (DMT-type contact) with increasing humidity. This is predicted by the Maugis model and is experimentally observed using optical interference fringes of equal chromatic order. We are able to separate the capillary condensation and solid-solid contributions to the adhesive force because the Maugis model allows a direct calculation of the area on which the Laplace pressure acts. At humidities approaching saturation the forces due to capillary condensation dominate monolayer-monolayer adhesion. At lower humidities both capillary condensation and direct monolayer-monolayer interaction contribute to the overall adhesion. © 2003 American Chemical Society.
• Su, Z., Cushman, J. H., & Curry, J. E. (2003). Computer simulation of anisotropic diffusion in monolayer films in mica slit pores. Journal of Chemical Physics, 118(Issue 3). doi:10.1063/1.1531073
  More info

  Molecular dynamics and grand canonical Monte Carlo simulations were conducted in order to understand better the relationship between the diffusion of octamethylcyclotetrasiloxane (OMCTS) and cyclohexane monolayers and the atomic structure of confining mica surfaces. It was found that diffusion increases with reduced fluid density. With the surface separation just large enough to accommodate a monolayer, lateral diffusion was direction dependent due to the influence of the atomically structured surfaces.
• Zhen, S. u., Cushman, J. H., & Curry, J. E. (2003). Computer simulation of anisotropic diffusion in monolayer films in mica slit pores. Journal of Chemical Physics, 118(3), 1417-1422.
  More info

  Abstract: Molecular dynamics and grand canonical Monte Carlo simulations were conducted in order to understand better the relationship between the diffusion of octamethylcyclotetrasiloxane (OMCTS) and cyclohexane monolayers and the atomic structure of confining mica surfaces. It was found that diffusion increases with reduced fluid density. With the surface separation just large enough to accommodate a monolayer, lateral diffusion was direction dependent due to the influence of the atomically structured surfaces.
• Curry, J., Farrell, J., Luo, J., Blowers, P., & Curry, J. E. (2002). Experimental and molecular mechanics and ab initio investigation of activated adsorption and desorption of trichloroethylene in mineral micropores. Environmental science & technology, 36(7).
  More info

  This research investigated activated adsorption of a hydrophobic organic contaminant(HOC) in mineral micropores using experimental and molecular modeling techniques. Adsorption of trichloroethylene (TCE) on a silica gel adsorbent was measured using a frontal analysis chromatography technique at atmospheric and elevated fluid pressures. Increasing the fluid pressure yielded increased TCE uptake that was not released upon lowering the pressure back to atmospheric conditions. This showed that the increase in pressure was able to rapidly induce the formation of a desorption-resistant fraction that previous investigations have shown requires months to develop at atmospheric pressure. Grand Canonical Monte Carlo (GCMC) modeling was then used to elucidate the nature of water and TCE behavior within silica micropores. The GCMC modeling showed that molecular scale packing restrictions resulted in pore fluid densities that ranged from 0.28 to 0.78 of those in the bulk solution. The modeling also showed that TCE was able to displace water from hydrophilic mineral pores due to molecular scale packing restrictions. Exothermic isosteric heats for TCE adsorption up to -27 kJ/mol were observed and were greatest in pores of 7 and 8 A. This indicated that TCE adsorption was energetically most favorable in pores that were minimally large enough to accommodate a TCE molecule. The pressure-induced uptake appeared to result primarily from an increase in the packing density in the smallest pores. Ab initio calculations showed that small distortions of a TCE molecule from its low energy conformation require high activation energies. Results from this study indicate that activated adsorption requiring bond angle distortions in the adsorbate may be responsible forthe slow attainment of adsorptive equilibrium of HOCs on microporous solids. Likewise, activated desorption from molecular-sized adsorption sites may contribute to the slow release of HOCs from aquifer sediments.
• Farrell, J., Luo, J., Blowers, P., & Curry, J. (2002). Experimental and molecular mechanics and Ab initio investigation of activated adsorption and desorption of trichloroethylene in mineral micropores. Environmental Science and Technology, 36(Issue 7). doi:10.1021/es011172e
  More info

  This research investigated activated adsorption of a hydrophobic organic contaminant (HOC) in mineral micropores using experimental and molecular modeling techniques. Adsorption of trichloroethylene (TCE) on a silica gel adsorbent was measured using a frontal analysis chromatography technique at atmospheric and elevated fluid pressures. Increasing the fluid pressure yielded increased TCE uptake that was not released upon lowering the pressure back to atmospheric conditions. This showed that the increase in pressure was able to rapidly induce the formation of a desorption-resistant fraction that previous investigations have shown requires months to develop at atmospheric pressure. Grand Canonical Monte Carlo (GCMC) modeling was then used to elucidate the nature of water and TCE behavior within silica micropores. The GCMC modeling showed that molecular scale packing restrictions resulted in pore fluid densities that ranged from 0.28 to 0.78 of those in the bulk solution. The modeling also showed that TCE was able to displace water from hydrophilic mineral pores due to molecular scale packing restrictions. Exothermic isosteric heats for TCE adsorption up to -27 kJ/mol were observed and were greatest in pores of 7 and 8 Å. This indicated that TCE adsorption was energetically most favorable in pores that were minimally large enough to accommodate a TCE molecule. The pressure-induced uptake appeared to result primarily from an increase in the packing density in the smallest pores. Ab initio calculations showed that small distortions of a TCE molecule from its low energy conformation require high activation energies. Results from this study indicate that activated adsorption requiring bond angle distortions in the adsorbate may be responsible for the slow attainment of adsorptive equilibrium of HOCs on microporous solids. Likewise, activated desorption from molecular-sized adsorption sites may contribute to the slow release of HOCs from aquifer sediments.
• Kim, S., Christenson, H. K., & Curry, J. E. (2002). The effect of humidity on the stability of an octadecyltriethoxysilane monolayer self-assembled on untreated and plasma-treated mica. Langmuir, 18(6), 2125-2129.
  More info

  Abstract: We investigated the stability of an octadecyltriethoxysilane (OTE) monolayer self-assembled on plasmatreated and untreated mica using a surface forces apparatus by measuring the thickness of the water layer that is adsorbed from vapor. The OTE monolayers are initially highly hydrophobic, but contact angle hysteresis indicates that water interacts favorably with the monolayers on prolonged exposure. Defects in the monolayer most likely make it possible for the water to reach the hydrophilic region between the silane headgroups and the mica. This explains why there has been very little success in measuring hydrophobic forces between OTE-coated mica surfaces. Hydrophobic forces between OTE surfaces have been successfully measured only with silica as the substrate. Even though these monolayers are not suitable for studies of the so-called hydrophobic force, they are ideal for studies designed to probe the interactions between the silane headgroups and mica. For a given relative humidity, the water film thickness is always less if the surfaces are plasma-treated before the monolayer is deposited. In the untreated case, water penetrates into the hydrophilic region between the monolayer and the mica. This does not occur in the plasma-treated case because the monolayer is more firmly anchored, most likely through covalent bonding.
• Kim, S., Christenson, H. K., & Curry, J. E. (2002). The effect of humidity on the stability of an octadecyltriethoxysilane monolayer self-assembled on untreated and plasma-treated mica. Langmuir, 18(Issue 6). doi:10.1021/la011020x
  More info

  We investigated the stability of an octadecyltriethoxysilane (OTE) monolayer self-assembled on plasmatreated and untreated mica using a surface forces apparatus by measuring the thickness of the water layer that is adsorbed from vapor. The OTE monolayers are initially highly hydrophobic, but contact angle hysteresis indicates that water interacts favorably with the monolayers on prolonged exposure. Defects in the monolayer most likely make it possible for the water to reach the hydrophilic region between the silane headgroups and the mica. This explains why there has been very little success in measuring hydrophobic forces between OTE-coated mica surfaces. Hydrophobic forces between OTE surfaces have been successfully measured only with silica as the substrate. Even though these monolayers are not suitable for studies of the so-called hydrophobic force, they are ideal for studies designed to probe the interactions between the silane headgroups and mica. For a given relative humidity, the water film thickness is always less if the surfaces are plasma-treated before the monolayer is deposited. In the untreated case, water penetrates into the hydrophilic region between the monolayer and the mica. This does not occur in the plasma-treated case because the monolayer is more firmly anchored, most likely through covalent bonding.
• Curry, J. E. (2001). The mica slit-pore as a tool to control the orientation and distortion of simple liquid monolayers. Molecular Physics, 99(9), 745-752.
  More info

  Abstract: Grand canonical ensemble Monte Carlo computer simulations have been used to study monolayer octamethylcyclotetrasiloxane (OMCTS) and cyclohexane films confined between mica-like surfaces to determine the effect of the mica surfaces on the orientation and distortion of the films at different surface alignments. The film molecules are packed as a highly ordered lattice. The orientation of the lattice is fixed relative to the mica surfaces and depends on the size of the film molecule. Registry shifts distort the film lattice by effectively stretching it along a particular direction that depends on the size of the film molecule. For a particular registry, OMCTS and cyclohexane monolayers are stretched in perpendicular directions. Coupling between the monolayers and the mica surfaces generates a nonzero shear stress when the surfaces are out of alignment, but the film does not become disordered or melt. It is possible that precisely controlled solid surfaces could be used to create packed arrays of film molecules with desired orientation and degree of distortion that may be useful in nanotechnological applications.
• Curry, J. E. (2001). The mica slit-pore as a tool to control the orientation and distortion of simple liquid monolayers. Molecular Physics, 99(Issue 9). doi:10.1080/00268970010027666
  More info

  Grand canonical ensemble Monte Carlo computer simulations have been used to study monolayer octamethylcyclotetrasiloxane (OMCTS) and cyclohexane films confined between mica-like surfaces to determine the effect of the mica surfaces on the orientation and distortion of the films at different surface alignments. The film molecules are packed as a highly ordered lattice. The orientation of the lattice is fixed relative to the mica surfaces and depends on the size of the film molecule. Registry shifts distort the film lattice by effectively stretching it along a particular direction that depends on the size of the film molecule. For a particular registry, OMCTS and cyclohexane monolayers are stretched in perpendicular directions. Coupling between the monolayers and the mica surfaces generates a nonzero shear stress when the surfaces are out of alignment, but the film does not become disordered or melt. It is possible that precisely controlled solid surfaces could be used to create packed arrays of film molecules with desired orientation and degree of distortion that may be useful in nanotechnological applications.
• Stroud, W. J., Curry, J. E., & Cushman, J. H. (2001). Capillary condensation and snap-off in nanoscale contacts. Langmuir, 17(3), 688-698.
  More info

  Abstract: When a surface is placed in a vapor, several layers of molecules may adsorb depending on the intermolecular forces involved. As two such surfaces are brought together, a critical point is reached at which the gas condenses between the surfaces, forming a capillary across the gap. A cohesive force is associated with the condensed bridge. The reverse process wherein the capillary bridge degenerates as the surfaces are moved apart is called snap-off. These processes play a profound role on scales from the nano to the macro. We have studied this phenomenon via isostrain grand canonical Monte Carlo statistical mechanical simulations for Lennard-Jones fluids. Specifically, we have examined capillary condensation and snap-off between nanocontacts, infinite rectilinear nanowires, and finite rectilinear nanoplatelets, where macroscale concepts and theories are just about impossible to apply. These results are compared to condensation between infinite parallel plates. We discuss our results in terms of the Kelvin equation and van der Waals film-thickening model.
• Stroud, W. J., Curry, J. E., & Cushman, J. H. (2001). Capillary condensation and snap-off in nanoscale contacts. Langmuir, 17(Issue 3). doi:10.1021/la0013143
  More info

  When a surface is placed in a vapor, several layers of molecules may adsorb depending on the intermolecular forces involved. As two such surfaces are brought together, a critical point is reached at which the gas condenses between the surfaces, forming a capillary across the gap. A cohesive force is associated with the condensed bridge. The reverse process wherein the capillary bridge degenerates as the surfaces are moved apart is called snap-off. These processes play a profound role on scales from the nano to the macro. We have studied this phenomenon via isostrain grand canonical Monte Carlo statistical mechanical simulations for Lennard-Jones fluids. Specifically, we have examined capillary condensation and snap-off between nanocontacts, infinite rectilinear nanowires, and finite rectilinear nanoplatelets, where macroscale concepts and theories are just about impossible to apply. These results are compared to condensation between infinite parallel plates. We discuss our results in terms of the Kelvin equation and van der Waals film-thickening model.
• Curry, J. E. (2000). Structure of a model lubricant in a mica slit pore. Journal of Chemical Physics, 113(6), 2400-2406.
  More info

  Abstract: The relationship between the interlayer structure of octamethylcyclotetrasiloxane (OMCTS) lubricant and the atomic structure of confining mica surfaces is examined by Monte Carlo simulation. Results exhibited a sufficient coupling between OMCTS and mica surfaces causing a fluid lattice distortion. The coupling resulted in a nonzero shear stress which is in good agreement with experimental shear stress results.
• Curry, J. E. (2000). Structure of a model lubricant in a mica slit pore. Journal of Chemical Physics, 113(Issue 6). doi:10.1063/1.482055
  More info

  The relationship between the interlayer structure of octamethylcyclotetrasiloxane (OMCTS) lubricant and the atomic structure of confining mica surfaces is examined by Monte Carlo simulation. Results exhibited a sufficient coupling between OMCTS and mica surfaces causing a fluid lattice distortion. The coupling resulted in a nonzero shear stress which is in good agreement with experimental shear stress results.
• Curry, J. E., & Cushman, J. H. (1998). Structure in confined fluids: Phase separation of binary simple liquid mixtures. Tribology Letters, 4(2), 129-136.
  More info

  Abstract: One- to five-layer cyclohexane and octamethyltetracyclosiloxane (OMCTS) films confined between mica-like surfaces are studied to elucidate changes in the lattice type and composition of the films. Grand canonical ensemble Monte Carlo computer simulations are used to study the laterally confined film. In contrast to previous studies, solid-like order is induced primarily by the strong fluid-solid interaction and is largely a function of pore width. Solid-like order within the layers causes the composition of the pore fluid to shift from the bulk composition, favoring either cyclohexane or OMCTS, depending on the pore width. A shift in the relative alignment of the surfaces perturbs the solid-like fluid structure but does not cause the sudden shear melting transition associated with epitaxial alignment of the fluid atoms with the surface.
• Curry, J. E., & Cushman, J. H. (1998). Structure in confined fluids: Phase separation of binary simple liquid mixtures. Tribology Letters, 4(Issue 2). doi:10.1023/a:1019163407805
  More info

  One- to five-layer cyclohexane and octamethyltetracyclosiloxane (OMCTS) films confined between mica-like surfaces are studied to elucidate changes in the lattice type and composition of the films. Grand canonical ensemble Monte Carlo computer simulations are used to study the laterally confined film. In contrast to previous studies, solid-like order is induced primarily by the strong fluid-solid interaction and is largely a function of pore width. Solid-like order within the layers causes the composition of the pore fluid to shift from the bulk composition, favoring either cyclohexane or OMCTS, depending on the pore width. A shift in the relative alignment of the surfaces perturbs the solid-like fluid structure but does not cause the sudden shear melting transition associated with epitaxial alignment of the fluid atoms with the surface.
• Curry, J. E., & Cushman, J. H. (1997). Normal-strain induced change in lattice-type for confined cyclohexane films. Materials Research Society Symposium - Proceedings, 464, 115-120.
  More info

  Abstract: One to three layer cyclohexane films confined between mica-like surfaces are studied to elucidate changes in the film's lattice-type. The laterally confined film in equilibrium with the bulk fluid that is well into the liquid regime of its phase diagram. Monte Carlo simulations are conducted at constant chemical potential, temperature, and V = Ah, where A is the lateral area and h is the separation between the walls. One and two layers of fluid freeze as h increases. The one layer fluid has a triangular lattice, while the two layer fluid exhibits first a square lattice and then a triangular lattice with increasing surface separation. In contrast to previous studies, solidlike order is induced primarily by the strong fluid-solid interaction and is largely a function of pore width. A shift in the relative alignment of the surfaces perturbs the solidlike fluid structure but does not cause the sudden shear melting transition associated with epitaxial alignment of the fluid atoms with the surface. There is a correlation between the shear stress calculated in the computer experiments and that measured in Surface Forces Apparatus experiments.
• Curry, J. E., & Christenson, H. K. (1996). Adsorption, wetting, and capillary condensation of nonpolar fluids in mica slits. Langmuir, 12(23), 5729-5735.
  More info

  Abstract: The adsorption behavior of n-pentane and cyclohexane in mica slits at room temperature has been studied as a function of chemical potential and gap width with multiple-beam interferometry. The measured film thicknesses close to saturation for large slit widths (effectively isolated surfaces) range up to 7 nm with n-pentane (at a relative vapor pressure of 0.9996) and 3 nm with cyclohexane (at a relative vapor pressure of 0.995). The thickness of these adsorbed wetting films is slightly larger than that predicted by van der Waals theory. The difference may be accounted for by thermal fluctuations of the adsorbed liquid-vapor interface. At smaller slit widths a capillary condensation transition occurs as the slit fills up with liquid. The separation at which this occurs is in good agreement with a film-thickening mechanism due to van der Waals forces across the gap only for the thickest films (t ≥ 6 nm). For thinner films the capillary condensation transition occurs at larger than expected slit widths, and the deviations are large for t ≤ 3 nm. We speculate that these larger-than-expected condensation separations are related to a fluctuation-enhanced film thickness in this regime. The work demonstrates the utility of measurements in a system consisting of a single slit-pore, without the complications of polydispersity and connectivity of pore networks. The results show that vapor adsorption isotherms can be measured with multiple-beam interferometry, i.e., in the surface force apparatus.
• Curry, J. E., & Christenson, H. K. (1996). Adsorption, wetting, and capillary condensation of nonpolar fluids in mica slits. Langmuir, 12(Issue 23). doi:10.1021/la960538b
  More info

  The adsorption behavior of n-pentane and cyclohexane in mica slits at room temperature has been studied as a function of chemical potential and gap width with multiple-beam interferometry. The measured film thicknesses close to saturation for large slit widths (effectively isolated surfaces) range up to 7 nm with n-pentane (at a relative vapor pressure of 0.9996) and 3 nm with cyclohexane (at a relative vapor pressure of 0.995). The thickness of these adsorbed wetting films is slightly larger than that predicted by van der Waals theory. The difference may be accounted for by thermal fluctuations of the adsorbed liquid-vapor interface. At smaller slit widths a capillary condensation transition occurs as the slit fills up with liquid. The separation at which this occurs is in good agreement with a film-thickening mechanism due to van der Waals forces across the gap only for the thickest films (t ≥ 6 nm). For thinner films the capillary condensation transition occurs at larger than expected slit widths, and the deviations are large for t ≤ 3 nm. We speculate that these larger-than-expected condensation separations are related to a fluctuation-enhanced film thickness in this regime. The work demonstrates the utility of measurements in a system consisting of a single slit-pore, without the complications of polydispersity and connectivity of pore networks. The results show that vapor adsorption isotherms can be measured with multiple-beam interferometry, i.e., in the surface force apparatus.
• Curry, J. E., & Cushman, J. H. (1996). Normal-Strain Induced Change in Lattice-Type for Confined Cyclohexane Films. MRS Proceedings, 464, 115-120. doi:10.1557/proc-464-115
  More info

  ABSTRACTOne to three layer cyclohexane films confined between mica-like surfaces are studied to elucidate changes in the films' lattice-type. The laterally confined film is in equilibrium with the bulk fluid that is well into the liquid regime of its phase diagram. Monte Carlo simulations are conducted at constant chemical potential, temperature, and V=Ah, where A is the lateral area and h is the separation between the walls. One and two layers of fluid freeze as h increases. The one layer fluid has a triangular lattice, while the two layer fluid exhibits first a square lattice and then a triangular lattice with increasing surface separation. In contrast to previous studies, solidlike order is induced primarily by the strong fluid-solid interaction and is largely a function of pore width. A shift in the relative alignment of the surfaces perturbs the solidlike fluid structure but does not cause the sudden shear melting transition associated with epitaxial alignment of the fluid atoms with the surface. There is a correlation between the shear stress calculated in the computer experiments and that measured in Surface Forces Apparatus experiments.
• Curry, J. E., & Cushman, J. H. (1995). BINARY MIXTURES OF SIMPLE FLUIDS IN STRUCTURED SLIT MICROPORES. Molecular Physics, 85(1), 173-192. doi:10.1080/00268979500101021
  More info

  The grand canonical Monte Carlo method is used to study a binary mixture of Lennard-Jones atoms confined to an atomically structured slit micropore which is in thermodynamic equilibrium with its bulk phase counterpart. In one example, the mixture consists of atoms of two distinct sizes, but with the same minimum depth in potential energy. In another example a binary mixture of different size atoms is again considered, but in the latter case the larger atom has a deeper potential energy minimum. Three mechanisms are found which influence selective adsorption of a mixture species: (i) liquid-like fluid layering, (ii) inplane solid-like ordering and (iii) molecular sieving. The large atoms are completely eliminated from the pore when the wall separation is physically too small for the large atoms to fit, or when both species physically fit in the pore and the small component epitaxially aligns with the surface or freezes. Complete elimination of the small species is not observed. A significant excess of larg...
• Curry, J. E., & Cushman, J. H. (1995). Mixtures in slit-micropores with pore-walls structured on both the atomic and nanoscale. Materials Research Society Symposium - Proceedings, 366, 141-152.
  More info

  Abstract: The grand canonical Monte Carlo method is used to study a binary mixture of Lennard-Jones atoms confined to various corrugated slit-micropores which are in thermodynamic equilibrium with their bulk phase counterpart. The micropore walls have the structure of the (100) face of an fcc lattice. In addition to this atomic scale structure, one wall possesses nanoscale structure in the form of rectilinear grooves (corrugation). The grooved surface divides the confined fluid film into two strip shaped regions. The confined film is studied in each region as a function of groove width, bulk phase composition, and the size of the wall atoms.
• Curry, J. E., & Cushman, J. H. (1995). Nanophase coexistence and sieving in binary mixtures confined between corrugated walls. The Journal of Chemical Physics, 103(6), 2132-2139.
  More info

  Abstract: The grand canonical Monte Carlo method is used to study a binary mixture of Lennard-Jones atoms confined to a corrugated slit micropore which is in thermodynamic equilibrium with its bulk phase counterpart. The micropore has atomically structured walls; one of the which possesses nanoscale structure in the form of rectilinear grooves (corrugation). The grooved surface divides the confined fluid film into two strip shaped regions, that inside and that outside the grooves. Transverse solidlike order in the film gives rise to shear stress. Transverse order coupled with packing restrictions give rise to a difference between the pore and bulk fluid mixture compositions. Solidlike order may appear within the grooves only, outside the grooves only, or in both regions simultaneously. As the relative alignment of the walls is shifted the pore fluid undergoes freeze-thaw cycles in one or both regions with associated changes in the shear stress and pore fluid composition. The degree of transverse order in the film is less than would be expected in a pure Lennard-Jones film and fluid-solid phase transitions are gradual as opposed to sudden as seen in pure Lennard-Jones films. The magnitude of the shear stress is greatest when a fluid-solid phase transition occurs in both regions of the pore. © 1995 American Institute of Physics.
• Curry, J. E., & Cushman, J. H. (1995). Nanophase coexistence and sieving in binary mixtures confined between corrugated walls. The Journal of Chemical Physics, 103(Issue 6). doi:10.1063/1.469690
  More info

  The grand canonical Monte Carlo method is used to study a binary mixture of Lennard-Jones atoms confined to a corrugated slit micropore which is in thermodynamic equilibrium with its bulk phase counterpart. The micropore has atomically structured walls; one of the which possesses nanoscale structure in the form of rectilinear grooves (corrugation). The grooved surface divides the confined fluid film into two strip shaped regions, that inside and that outside the grooves. Transverse solidlike order in the film gives rise to shear stress. Transverse order coupled with packing restrictions give rise to a difference between the pore and bulk fluid mixture compositions. Solidlike order may appear within the grooves only, outside the grooves only, or in both regions simultaneously. As the relative alignment of the walls is shifted the pore fluid undergoes freeze-thaw cycles in one or both regions with associated changes in the shear stress and pore fluid composition. The degree of transverse order in the film is less than would be expected in a pure Lennard-Jones film and fluid-solid phase transitions are gradual as opposed to sudden as seen in pure Lennard-Jones films. The magnitude of the shear stress is greatest when a fluid-solid phase transition occurs in both regions of the pore. © 1995 American Institute of Physics.
• Curry, J. E., & Cushman, J. H. (1994). Mixtures in Slit-Micropores with Pore-Walls Structured on Both the Atomic and Nanoscale. MRS Proceedings, 366, 141-152. doi:10.1557/proc-366-141
  More info

  ABSTRACTThe grand canonical Monte Carlo method is used to study a binary mixture of Lennard-Jones atoms confined to various corrugated slit-micropores which are in thermodynamic equilibrium with their bulk phase counterpart. The micropore walls have the structure of the (100) face of an fcc lattice. In addition to this atomic scale structure, one wall possesses nanoscale structure in the form of rectilinear grooves (corrugation). The grooved surface divides the confined fluid film into two strip shaped regions. The confined film is studied in each region as a function of groove width, bulk phase composition, and the size of the wall atoms.
• Curry, J. E., Cushman, J. H., Diestler, D. J., & Schoen, M. (1994). Interfacial tension in confined molecularly-thin films. Molecular Physics, 81(5), 1059-1073. doi:10.1080/00268979400100711
  More info

  The grand-canonical ensemble Monte Carlo method has been used to study the interfacial tension in a rare-gas film confined to a slit pore whose plane-parallel walls comprise rigidly fixed similar rare-gas atoms. In narrow pores, where both walls strongly influence the whole film, the interfacial tension is shown to be a highly complex function of pore width and transverse alignment of the walls. Oscillations in the tension are correlated with the addition of new fluid layers, the most highly structured layers corresponding to maxima in the tension. Separate interlayer and intralayer contributions to the tension are defined and shown to be useful in explaining the physics of the change in the interfacial tension with the addition of new layers to the film.
• Curry, J. E., Zhang, F., Cushman, J. H., Schoen, M., & Diestler, D. J. (1994). Transient coexisting nanophases in ultrathin films confined between corrugated walls. The Journal of Chemical Physics, 101(12), 10824-10832.
  More info

  Abstract: Grand-canonical Monte Carlo and microcanonical molecular dynamics methods have been used to simulate an ultrathin monatomic film confined to a slit-pore [i.e., between solid surfaces (walls)]. Both walls comprise atoms rigidly fixed in the face centered cubic (100) configuration; one wall is smooth on a nanoscale and the other is corrugated (i.e., scored with regularly spaced rectilinear grooves one to several nanometers wide). Properties of the film have been computed as a function of the lateral alignment (registry), with the temperature, chemical potential, and distance between the walls kept constant. Changing the registry carries the film through a succession of equilibrium states, ranging from all solid at one extreme to all fluid at the other. Over a range of intermediate registries the film consists of fluid and solid portions in equilibrium, that is fluid-filled nanocapillaries separated by solid strips. The range of registries over which such fluid-solid equilibria exist depends upon the width of the grooves and the frequency of the corrugation. For grooves of width comparable to the range of the interatomic potential, fluid and solid phases cease to coexist. In the limit of very wide grooves the character of the film is similar to that of the film confined by strictly smooth walls. The rich phase behavior of the confined film due to the coupling between molecular (registry) and nano (corrugation) scales has obvious implications for boundary lubrication. © 1994 American Institute of Physics.
• Curry, J. E., Zhang, F., Cushman, J. H., Schoen, M., & Diestler, D. J. (1994). Transient coexisting nanophases in ultrathin films confined between corrugated walls. The Journal of Chemical Physics, 101(Issue 12). doi:10.1063/1.467831
  More info

  Grand-canonical Monte Carlo and microcanonical molecular dynamics methods have been used to simulate an ultrathin monatomic film confined to a slit-pore [i.e., between solid surfaces (walls)]. Both walls comprise atoms rigidly fixed in the face centered cubic (100) configuration; one wall is smooth on a nanoscale and the other is corrugated (i.e., scored with regularly spaced rectilinear grooves one to several nanometers wide). Properties of the film have been computed as a function of the lateral alignment (registry), with the temperature, chemical potential, and distance between the walls kept constant. Changing the registry carries the film through a succession of equilibrium states, ranging from all solid at one extreme to all fluid at the other. Over a range of intermediate registries the film consists of fluid and solid portions in equilibrium, that is fluid-filled nanocapillaries separated by solid strips. The range of registries over which such fluid-solid equilibria exist depends upon the width of the grooves and the frequency of the corrugation. For grooves of width comparable to the range of the interatomic potential, fluid and solid phases cease to coexist. In the limit of very wide grooves the character of the film is similar to that of the film confined by strictly smooth walls. The rich phase behavior of the confined film due to the coupling between molecular (registry) and nano (corrugation) scales has obvious implications for boundary lubrication. © 1994 American Institute of Physics.
• Diestler, D. J., Schoen, M., Curry, J. E., & Cushman, J. H. (1994). Thermodynamics of a fluid confined to a slit pore with structured walls. The Journal of Chemical Physics, 100(12), 9140-9146.
  More info

  Abstract: In this article we extend our previous thermodynamic analysis of films confined to slit pores with smooth walls (i.e., plane-parallel solid surfaces without molecular structure) to the situation in which the walls themselves possess structure. Structured-wall models are frequently employed to interpret experiments performed with the surface forces apparatus (SFA), in which thin films (1-10 molecular diameters thick) are subjected to shear stress by moving the walls laterally over one another at constant temperature, chemical potential, and normal stress or load. The periodic structure of the walls is reflected in a periodic variation of the shear stress with the lateral alignment (i.e., shear strain) of the walls. We demonstrate by means of a solvable two-dimensional model that the molecular length scale imposed by the structure of the walls precludes the derivation of a simple mechanical expression for the grand potential analogous to that which holds in the smooth-wall case. This conclusion is borne out by the results of a grand-canonical Monte Carlo simulation of the three-dimensional prototypal model consisting of a Leonard-Jones (12,6) fluid confined between fcc (100) walls. Criteria for the thermodynamic stability of thin films confined by structured walls are derived and applied to the SFA. © 1994 American Institute of Physics.
• Diestler, D. J., Schoen, M., Curry, J. E., & Cushman, J. H. (1994). Thermodynamics of a fluid confined to a slit pore with structured walls. The Journal of Chemical Physics, 100(Issue 12). doi:10.1063/1.466668
  More info

  In this article we extend our previous thermodynamic analysis of films confined to slit pores with smooth walls (i.e., plane-parallel solid surfaces without molecular structure) to the situation in which the walls themselves possess structure. Structured-wall models are frequently employed to interpret experiments performed with the surface forces apparatus (SFA), in which thin films (1-10 molecular diameters thick) are subjected to shear stress by moving the walls laterally over one another at constant temperature, chemical potential, and normal stress or load. The periodic structure of the walls is reflected in a periodic variation of the shear stress with the lateral alignment (i.e., shear strain) of the walls. We demonstrate by means of a solvable two-dimensional model that the molecular length scale imposed by the structure of the walls precludes the derivation of a simple mechanical expression for the grand potential analogous to that which holds in the smooth-wall case. This conclusion is borne out by the results of a grand-canonical Monte Carlo simulation of the three-dimensional prototypal model consisting of a Leonard-Jones (12,6) fluid confined between fcc (100) walls. Criteria for the thermodynamic stability of thin films confined by structured walls are derived and applied to the SFA. © 1994 American Institute of Physics.
• Curry, J. E., & McQuarrie, D. A. (1992). On dielectric saturation modeling in a continuum solvent. Journal of Colloid And Interface Science, 154(1), 289-294.
  More info

  Abstract: The linear Poisson-Boltzmann equation is solved with a variable dielectric constant to account for dielectric saturation. Two different spatially dependent forms of the dielectric constant are compared. It is shown that the electrostatic repulsion between two flat plates is decreased by dielectric saturation and that it depends in a complicated way on both the dielectric constant and the electric field. © 1992.
• Curry, J. E., & McQuarrie, D. A. (1992). On dielectric saturation modeling in a continuum solvent. Journal of Colloid And Interface Science, 154(Issue 1). doi:10.1016/0021-9797(92)90102-r
  More info

  The linear Poisson-Boltzmann equation is solved with a variable dielectric constant to account for dielectric saturation. Two different spatially dependent forms of the dielectric constant are compared. It is shown that the electrostatic repulsion between two flat plates is decreased by dielectric saturation and that it depends in a complicated way on both the dielectric constant and the electric field. © 1992.
• Curry, J. E., & McQuarrie, D. A. (1992). On the Effect of Dielectric Saturation on the Swelling of Clays. Langmuir, 8(Issue 3). doi:10.1021/la00039a047
  More info

  The nonlinear Poisson-Boltzmann equation is solved with a field-dependent expression for the dielectric constant to determine the effect of dielectric saturation on swelling pressure in clays. Calculations including a scaled and an unsealed version of the approximate expression for the field-dependent dielectric constant first derived by Booth are compared. It is found that the swelling pressure decreases in all cases considered; however, the effect is significant only when the electric field at the surface is high enough to cause dielectric saturation. Nonlinear dielectric effects should be considered in models which predict surface electric fields in excess of 107 V·m-1. © 1992, American Chemical Society. All rights reserved.
• Curry, J. E., & McQuarrie, D. A. (1992). On the effect of dielectric saturation on the swelling of clays. Langmuir, 8(3), 1026-1029.
  More info

  Abstract: The nonlinear Poisson-Boltzmann equation is solved with a field-dependent expression for the dielectric constant to determine the effect of dielectric saturation on swelling pressure in clays. Calculations including a scaled and an unscaled version of the approximate expression for the field-dependent dielectric constant first derived by Booth are compared. It is found that the swelling pressure decreases in all cases considered; however, the effect is significant only when the electric field at the surface is high enough to cause dielectric saturation. Nonlinear dielectric effects should be considered in models which predict surface electric fields in excess of 107 V·m-1.
• Huerta, M. M., Curry, J. E., & McQuarrie, D. A. (1992). The effect of unequal ionic size on the swelling pressure in clays. Clays & Clay Minerals, 40(5), 491-500.
  More info

  Abstract: The Gouy-Chapman theory is applied to a 1:1 electrolyte to show that the coion size is only important at surface charge densities much lower than those found in typical clay systems. Next the model is applied to a 1:1 and 2:1 electrolyte mixture with unequal-sized counterions to show the swelling pressure is highly dependent on both counterion sizes. -from Authors
• Huerta, M. M., Curry, J. E., & McQuarrie, D. A. (1992). The effect of unequal ionic size on the swelling pressure in clays. Clays and Clay Minerals, 40(Issue 5). doi:10.1346/ccmn.1992.0400502
  More info

  In this paper, we use the unequal radius modified Gouy-Chapman theory to evaluate the effect of the ionic size of the electrolyte on the swelling pressures (II) in different clay systems immersed in electrolytic solutions. First the model is applied to a 1:1 electrolyte to show that the coion size is only important at surface charge densities much lower than those found in typical clay systems. The swelling pressure is calculated and the results are compared with experimental data. Literature ionic radii values are used to show the dependence of the swelling pressure on the specific counterions present. Next the model is applied to a 1:1 and 2:1 electrolyte mixture with unequal-sized counterions to show the swelling pressure is highly dependent on both counterion sizes. The unequal and same-sized cases are compared. © 1992, The Clay Minerals Society.
• Curry, J. E., Feller, S. E., & McQuarrie, D. A. (1991). A variational solution of the nonlinear poisson-boltzmann equation inside a spherical cavity. Journal of Colloid And Interface Science, 143(2), 527-531.
  More info

  Abstract: The nonlinear Poisson-Boltzmann equation is solved variationally to obtain the electrostatic potential profile in a spherical cavity containing an aqueous electrolyte solution. The variational solution is based on the linear solution to the Poisson-Boltzmann equation. It is found that a three-parameter trial function provides sufficient accuracy to make the variational potential profile indistinguishable from exact numerical results. The variational solution is valid over the concentration, size, and surface potential ranges typical of phospholipid vesicles. It is anticipated that this solution will be useful in determining the stability of membraneous vesicles and reverse micelles. © 1991.
• Curry, J. E., Feller, S. E., & McQuarrie, D. A. (1991). A variational solution of the nonlinear poisson-boltzmann equation inside a spherical cavity. Journal of Colloid And Interface Science, 143(Issue 2). doi:10.1016/0021-9797(91)90285-g
  More info

  The nonlinear Poisson-Boltzmann equation is solved variationally to obtain the electrostatic potential profile in a spherical cavity containing an aqueous electrolyte solution. The variational solution is based on the linear solution to the Poisson-Boltzmann equation. It is found that a three-parameter trial function provides sufficient accuracy to make the variational potential profile indistinguishable from exact numerical results. The variational solution is valid over the concentration, size, and surface potential ranges typical of phospholipid vesicles. It is anticipated that this solution will be useful in determining the stability of membraneous vesicles and reverse micelles. © 1991.

Proceedings Publications

• Heo, C. H., Maier, R. M., & Curry, J. E. (2006). Directly measuring the adhesive and elastic properties of bacteria using a surface force apparatus: Effect of desiccation. In 2006 MRS Spring Meeting, 925.
  More info

  Bacterial adhesion is the first step in biofilm formation which impacts numerous environmental, industrial and medical processes. Examples of undesirable consequences of biofilm formation include metal rust, sewage sludge and bacteria-related diseases. Desirable consequences are biofiltration and bioremediation. Bacteria are resilient and can survive in harsh environments. A severe stress is desiccation since dehydration can damage DNA and change the properties of proteins. Some bacteria protect against dehydration by accumulating sugars such as sucrose and trehalose while others undergo a transformation from an active to a dormant state. Evaporative deposition of bacteria on a surface shows that some bacteria aggregate to form two dimensional patterns which may be important for nutrient sharing and survival in dry conditions'. Since bacteria are increasingly being employed as components in biosensors and biofilm reactors, it is important to understand the material properties of bacteria in dry conditions for these applications. For a decade, Atomic Force Microscopy (AFM) has been the primary tool used to study the adhesion and elastic properties of individual bacteria. In this work we show it is possible to use a Surface Forces Apparatus (SFA) to measure elastic and adhesive properties of small collections of surface bound bacteria. The measurements are conducted with incomplete, patterned bacterial films and we have developed a protocol to image the contact area with AFM after the experiment. Using the SFA, we measured the force profile between a Pseudomonas aeruginosa PAO1 film and a bare mica surface. P. aeruginosa PAO1 is a . ubiquitous gram-negative soil bacterium and is also an opportunistic pathogen. We repeated the measurement in the same contact position for six days to determine the effect of desiccation on the film material properties. © 2006 Materials Research Society.
• Farrell, J., Luo, J., Blowers, P., & Curry, J. (2000). Square pegs, round holes and slow desorption. In 220th ACS National Meeting, 40.
  More info

  Predicting the transport and fate of hydrophobic organic contaminants in underground aquifers requires a mechanistic understanding of sediment-contaminant interactions. A rapid, pressure induced formation of a desorption resistant fraction of trichloroethylene (TCE) on three model adsorbents, i.e., silica gel, hydrophobic Y-zeolite, and polyvinyl chloride beads, was studied. Quantum mechanical calculations were performed to determine the energy associated with distorting the bond angles in a TCE molecule from their equilibrium configuration. Atomistic simulations were performed to determine the effect of separation distance on intermolecular repulsions between a TCE molecule and a silica surface. The effect of pressure on TCE adsorption was small or negligible after the first pressure step. TCE adsorption and desorption on this silica gel were completely reversible for short equilibration times, but a desorption resistant fraction could be induced by equilibration times longer than 1 day. The TCE pressure induced adsorption occurred in pores smaller than the effective size of a TCE molecule at 1 bar. The energies associated with even small molecular distortions could lead to high activation energies for desorption. Increasing contaminant sequestration with increasing contact time might be attributed to the activation energy required for penetrating pores smaller than the equilibrium size of the adsorbate molecule. The rapid development of desorption resistant TCE on the silica gel suggested that the diffusional distances associated with this mechanisms were small.

Presentations

• Curry, J. (2011, March). Evaporative Deposition Patterns of Bacteria from a Sessile Drop. Society for Industrial and Applied Mathematics, National meetingSociety for Industrial and Applied Mathematics.

Poster Presentations

• Curry, J. E., West, D., & Forbush, K. (2014, April). Evaporation of water droplets containing particles on the surface of muscovite mica: Effect of changes in hydrophobicity, evaporation, and particle distribution from atmospheric exposure. Earth Week poster event. University of Arizona.
• McOmber, T. C., Rock, C. M., Mclain, J. E., & Curry, J. E. (2014, January). Water quality improvements for Southern Arizona on the Upper Santa Cruz River. Arizona Water Association Research Workshop. Tempe, Arizona.
• Mclain, J. E., Rock, C. M., Curry, J. E., McOmber, T., Mclain, J. E., Rock, C. M., Curry, J. E., & McOmber, T. (2013, October). Water quality improvements for Southern Arizona on the Upper Santa Cruz River. University of Arizona Food Safety Consortium Annual Meeting. Tucson, Arizona: UA-Food Safety Consortium.
  More info

  Poster presentation of Master's Level Research.