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• 1. [Image] Initial Investigation of Soil Mercury Geochemistry as an Aid to Drill Site Selection in Geothermal Systems

  	A mercury-in-soil survey was conducted at the Roosevelt Hot Springs Known Geothermal Resource Area (KGRA), Utah, to evaluate mercury soil geochemistry as a method of selecting exploration well sites in ...
  	Citation × Citation Citation Abstract Copy Title: Initial Investigation of Soil Mercury Geochemistry as an Aid to Drill Site Selection in Geothermal Systems Author: Capuano, R.M. Year: 1978 A mercury-in-soil survey was conducted at the Roosevelt Hot Springs Known Geothermal Resource Area (KGRA), Utah, to evaluate mercury soil geochemistry as a method of selecting exploration well sites in a hot-water geothermal system. Samples of -80 mesh soil were collected at 30.5 m intervals along traverses crossing known structures, surficial geothermal alteration, and exploration well sites, and were analyzed using a Gold Film Mercury Detector. Strong mercury anomalies occur at locations along known structures in close proximity to subsurface thermal activity; examples include areas over hot spring deposits and near a shallow producing well. In contrast, background mercury concentrations are present in nearby locations with little or no indication of subsurface thermal activity, such as areas around deep marginal producing wells and dry wells, and areas lacking hot spring deposits. These results indicate that mercury geochemical surveys can be useful for identifying and mapping structures controlling fluid flow in geothermal systems and for delineating areas overlying near-surface thermal activity. Soil mercury geochemistry thus provides information which may aid in the cost-effective selection of exploratory well sites Title: Initial Investigation of Soil Mercury Geochemistry as an Aid to Drill Site Selection in Geothermal Systems Author: Capuano, R.M. Year: 1978 A mercury-in-soil survey was conducted at the Roosevelt Hot Springs Known Geothermal Resource Area (KGRA), Utah, to evaluate mercury soil geochemistry as a method of selecting exploration well sites in a hot-water geothermal system. Samples of -80 mesh soil were collected at 30.5 m intervals along traverses crossing known structures, surficial geothermal alteration, and exploration well sites, and were analyzed using a Gold Film Mercury Detector. Strong mercury anomalies occur at locations along known structures in close proximity to subsurface thermal activity; examples include areas over hot spring deposits and near a shallow producing well. In contrast, background mercury concentrations are present in nearby locations with little or no indication of subsurface thermal activity, such as areas around deep marginal producing wells and dry wells, and areas lacking hot spring deposits. These results indicate that mercury geochemical surveys can be useful for identifying and mapping structures controlling fluid flow in geothermal systems and for delineating areas overlying near-surface thermal activity. Soil mercury geochemistry thus provides information which may aid in the cost-effective selection of exploratory well sites Close

• 2. [Article] A Facile Route to Tailoring Peptide-Stabilized Gold Nanoparticles Using Glutathione as a Synthon

  The preparation of gold nanoparticles (AuNPs) of high purity and stability remains a major challenge for biological applications. This paper reports a simple synthetic strategy to prepare water-soluble ...

  Citation × Citation Citation Abstract Copy Title: A Facile Route to Tailoring Peptide-Stabilized Gold Nanoparticles Using Glutathione as a Synthon Author: Ho Wu, Rosina, Nguyen, Tan P., Marquart, Grant W., Miesen, Thomas J., Mau, Theresa, Mackiewicz, Marilyn R. Year: 2014 The preparation of gold nanoparticles (AuNPs) of high purity and stability remains a major challenge for biological applications. This paper reports a simple synthetic strategy to prepare water-soluble peptide-stabilized AuNPs. Reduced glutathione, a natural tripeptide, was used as a synthon for the growth of two peptide chains directly on the AuNP surface. Both nonpolar (tryptophan and methionine) and polar basic (histidine and dansylated arginine) amino acids were conjugated to the GSH-capped AuNPs. Ultracentrifugation concentrators with polyethersulfone (PES) membranes were used to purify precursor materials in each stage of the multi-step synthesis to minimize side reactions. Thin layer chromatography, transmission electron microscopy, UV-Visible, 1H-NMR, and fluorescence spectroscopies demonstrated that ultracentrifugation produces high purity AuNPs, with narrow polydispersity, and minimal aggregation. More importantly, it allows for more control over the composition of the final ligand structure. Studies under conditions of varying pH and ionic strength revealed that peptide length, charge, and hydrophobicity influence the stability as well as solubility of the peptide-capped AuNPs. The synthetic and purification strategies used provide a facile route for developing a library of tailored biocompatible peptide-stabilized AuNPs for biomedical applications. Title: A Facile Route to Tailoring Peptide-Stabilized Gold Nanoparticles Using Glutathione as a Synthon Author: Ho Wu, Rosina, Nguyen, Tan P., Marquart, Grant W., Miesen, Thomas J., Mau, Theresa, Mackiewicz, Marilyn R. Year: 2014 The preparation of gold nanoparticles (AuNPs) of high purity and stability remains a major challenge for biological applications. This paper reports a simple synthetic strategy to prepare water-soluble peptide-stabilized AuNPs. Reduced glutathione, a natural tripeptide, was used as a synthon for the growth of two peptide chains directly on the AuNP surface. Both nonpolar (tryptophan and methionine) and polar basic (histidine and dansylated arginine) amino acids were conjugated to the GSH-capped AuNPs. Ultracentrifugation concentrators with polyethersulfone (PES) membranes were used to purify precursor materials in each stage of the multi-step synthesis to minimize side reactions. Thin layer chromatography, transmission electron microscopy, UV-Visible, 1H-NMR, and fluorescence spectroscopies demonstrated that ultracentrifugation produces high purity AuNPs, with narrow polydispersity, and minimal aggregation. More importantly, it allows for more control over the composition of the final ligand structure. Studies under conditions of varying pH and ionic strength revealed that peptide length, charge, and hydrophobicity influence the stability as well as solubility of the peptide-capped AuNPs. The synthetic and purification strategies used provide a facile route for developing a library of tailored biocompatible peptide-stabilized AuNPs for biomedical applications. Close

• 3. [Article] Aqueous Red-Emitting Silicon Nanoparticles for Cellular Imaging: Consequences of Protecting Against Surface Passivation by Hydroxide and Water for Stable Red Emission

  Stable, aqueous, red-to-near infrared emission is critical for the use of silicon nanoparticles (Si NPs) in biological fluorescence assays, but such Si NPs have been difficult to attain. We report a synthesis ...

  Citation × Citation Citation Abstract Copy Title: Aqueous Red-Emitting Silicon Nanoparticles for Cellular Imaging: Consequences of Protecting Against Surface Passivation by Hydroxide and Water for Stable Red Emission Author: Chiu, Sheng-Kuei, Manhat, Beth Ann, DeBenedetti, William J.I., Brown, Anna L., Fichter, Katye, Vu, Tania, Eastman, Micah, Jiao, Jun, Goforth, Andrea Mitchell Year: 2013 Stable, aqueous, red-to-near infrared emission is critical for the use of silicon nanoparticles (Si NPs) in biological fluorescence assays, but such Si NPs have been difficult to attain. We report a synthesis and surface modification strategy that protects Si NPs and preserves red photoluminescence (PL) in water for more than 6 mo. The Si NPs were synthesized via high temperature reaction, liberated from an oxide matrix, and functionalized via hydrosilylation to yield hydrophobic particles. The hydrophobic Si NPs were phase transferred to water using the surfactant cetyltrimethylammonium bromide (CTAB) with retention of red PL. CTAB apparently serves a double role in providing stable, aqueous, red-emitting Si NPs by (i) forming a hydrophobic barrier between the Si NPs and water and (ii) providing aqueous colloidal stability via the polar head group. We demonstrate preservation of the aqueous red emission of these Si NPs in biological media and examine the effects of pH on emission color. Title: Aqueous Red-Emitting Silicon Nanoparticles for Cellular Imaging: Consequences of Protecting Against Surface Passivation by Hydroxide and Water for Stable Red Emission Author: Chiu, Sheng-Kuei, Manhat, Beth Ann, DeBenedetti, William J.I., Brown, Anna L., Fichter, Katye, Vu, Tania, Eastman, Micah, Jiao, Jun, Goforth, Andrea Mitchell Year: 2013 Stable, aqueous, red-to-near infrared emission is critical for the use of silicon nanoparticles (Si NPs) in biological fluorescence assays, but such Si NPs have been difficult to attain. We report a synthesis and surface modification strategy that protects Si NPs and preserves red photoluminescence (PL) in water for more than 6 mo. The Si NPs were synthesized via high temperature reaction, liberated from an oxide matrix, and functionalized via hydrosilylation to yield hydrophobic particles. The hydrophobic Si NPs were phase transferred to water using the surfactant cetyltrimethylammonium bromide (CTAB) with retention of red PL. CTAB apparently serves a double role in providing stable, aqueous, red-emitting Si NPs by (i) forming a hydrophobic barrier between the Si NPs and water and (ii) providing aqueous colloidal stability via the polar head group. We demonstrate preservation of the aqueous red emission of these Si NPs in biological media and examine the effects of pH on emission color. Close

• 4. [Article] A Facile Route to Tailoring Peptide-Stabilized Gold Nanoparticles Using Glutathione as a Synthon

  The preparation of gold nanoparticles (AuNPs) of high purity and stability remains a major challenge for biological applications. This paper reports a simple synthetic strategy to prepare water-soluble ...

  Citation × Citation Citation Abstract Copy Title: A Facile Route to Tailoring Peptide-Stabilized Gold Nanoparticles Using Glutathione as a Synthon Author: Ho Wu, Rosina, Nguyen, Tan P., Marquart, Grant W., Miesen, Thomas J., Mau, Theresa, Mackiewicz, Marilyn R. Year: 2014 The preparation of gold nanoparticles (AuNPs) of high purity and stability remains a major challenge for biological applications. This paper reports a simple synthetic strategy to prepare water-soluble peptide-stabilized AuNPs. Reduced glutathione, a natural tripeptide, was used as a synthon for the growth of two peptide chains directly on the AuNP surface. Both nonpolar (tryptophan and methionine) and polar basic (histidine and dansylated arginine) amino acids were conjugated to the GSH-capped AuNPs. Ultracentrifugation concentrators with polyethersulfone (PES) membranes were used to purify precursor materials in each stage of the multi-step synthesis to minimize side reactions. Thin layer chromatography, transmission electron microscopy, UV-Visible, 1H-NMR, and fluorescence spectroscopies demonstrated that ultracentrifugation produces high purity AuNPs, with narrow polydispersity, and minimal aggregation. More importantly, it allows for more control over the composition of the final ligand structure. Studies under conditions of varying pH and ionic strength revealed that peptide length, charge, and hydrophobicity influence the stability as well as solubility of the peptide-capped AuNPs. The synthetic and purification strategies used provide a facile route for developing a library of tailored biocompatible peptide-stabilized AuNPs for biomedical applications. Title: A Facile Route to Tailoring Peptide-Stabilized Gold Nanoparticles Using Glutathione as a Synthon Author: Ho Wu, Rosina, Nguyen, Tan P., Marquart, Grant W., Miesen, Thomas J., Mau, Theresa, Mackiewicz, Marilyn R. Year: 2014 The preparation of gold nanoparticles (AuNPs) of high purity and stability remains a major challenge for biological applications. This paper reports a simple synthetic strategy to prepare water-soluble peptide-stabilized AuNPs. Reduced glutathione, a natural tripeptide, was used as a synthon for the growth of two peptide chains directly on the AuNP surface. Both nonpolar (tryptophan and methionine) and polar basic (histidine and dansylated arginine) amino acids were conjugated to the GSH-capped AuNPs. Ultracentrifugation concentrators with polyethersulfone (PES) membranes were used to purify precursor materials in each stage of the multi-step synthesis to minimize side reactions. Thin layer chromatography, transmission electron microscopy, UV-Visible, 1H-NMR, and fluorescence spectroscopies demonstrated that ultracentrifugation produces high purity AuNPs, with narrow polydispersity, and minimal aggregation. More importantly, it allows for more control over the composition of the final ligand structure. Studies under conditions of varying pH and ionic strength revealed that peptide length, charge, and hydrophobicity influence the stability as well as solubility of the peptide-capped AuNPs. The synthetic and purification strategies used provide a facile route for developing a library of tailored biocompatible peptide-stabilized AuNPs for biomedical applications. Close

• 5. [Article] The Atmosphere can be a Source of Certain Water Soluble Volatile Organic Compounds in Urban Streams

  Surface water and air volatile organic compound (VOC) data from 10 U. S. Geological Survey monitoring sites were used to evaluate the potential for direct transport of VOCs from the atmosphere to urban ...

  Citation × Citation Citation Abstract Copy Title: The Atmosphere can be a Source of Certain Water Soluble Volatile Organic Compounds in Urban Streams Author: Kenner, Scott J, Bender, David A., Pankow, James F., Zogorski, John S. Year: 2014 Surface water and air volatile organic compound (VOC) data from 10 U. S. Geological Survey monitoring sites were used to evaluate the potential for direct transport of VOCs from the atmosphere to urban streams. Analytical results of 87 VOC compounds were screened by evaluating the occurrence and detection levels in both water and air, and equilibrium concentrations in water (C-w(s)) based on the measured air concentrations. Four compounds (acetone, methyl tertiary butyl ether, toluene, and m- & p-xylene) were detected in more than 20% of water samples, in more than 10% of air samples, and more than 10% of detections in air were greater than long-term method detection levels (LTMDL) in water. Benzene was detected in more than 20% of water samples and in more than 10% of air samples. Two percent of benzene detections in air were greater than one-half the LTMDL in water. Six compounds (chloroform, p-isopropyltoluene, methylene chloride, perchloroethene, 1,1,1-trichloroethane, and trichloroethene) were detected in more than 20% of water samples and in more than 10% of air samples. Five VOCs, toluene, m- & p-xylene, methyl tert-butyl ether (MTBE), acetone, and benzene were identified as having sufficiently high concentrations in the atmosphere to be a source to urban streams. MTBE, acetone, and benzene exhibited behavior that was consistent with equilibrium concentrations in the atmosphere. Title: The Atmosphere can be a Source of Certain Water Soluble Volatile Organic Compounds in Urban Streams Author: Kenner, Scott J, Bender, David A., Pankow, James F., Zogorski, John S. Year: 2014 Surface water and air volatile organic compound (VOC) data from 10 U. S. Geological Survey monitoring sites were used to evaluate the potential for direct transport of VOCs from the atmosphere to urban streams. Analytical results of 87 VOC compounds were screened by evaluating the occurrence and detection levels in both water and air, and equilibrium concentrations in water (C-w(s)) based on the measured air concentrations. Four compounds (acetone, methyl tertiary butyl ether, toluene, and m- & p-xylene) were detected in more than 20% of water samples, in more than 10% of air samples, and more than 10% of detections in air were greater than long-term method detection levels (LTMDL) in water. Benzene was detected in more than 20% of water samples and in more than 10% of air samples. Two percent of benzene detections in air were greater than one-half the LTMDL in water. Six compounds (chloroform, p-isopropyltoluene, methylene chloride, perchloroethene, 1,1,1-trichloroethane, and trichloroethene) were detected in more than 20% of water samples and in more than 10% of air samples. Five VOCs, toluene, m- & p-xylene, methyl tert-butyl ether (MTBE), acetone, and benzene were identified as having sufficiently high concentrations in the atmosphere to be a source to urban streams. MTBE, acetone, and benzene exhibited behavior that was consistent with equilibrium concentrations in the atmosphere. Close

• 6. [Article] Hydrophobic Surfactant Proteins Strongly Induce Negative Curvature

  The hydrophobic surfactant proteins SP-B and SP-C greatly accelerate the adsorption of vesicles containing the surfactant lipids to form a film that lowers the surface tension of the air/water interface ...

  Citation × Citation Citation Abstract Copy Title: Hydrophobic Surfactant Proteins Strongly Induce Negative Curvature Author: Chavarha, Mariya, Loney, Ryan W., Rananavare, Shankar B., Hall, Stephen B. Year: 2015 The hydrophobic surfactant proteins SP-B and SP-C greatly accelerate the adsorption of vesicles containing the surfactant lipids to form a film that lowers the surface tension of the air/water interface in the lungs. Pulmonary surfactant enters the interface by a process analogous to the fusion of two vesicles. As with fusion, several factors affect adsorption according to how they alter the curvature of lipid leaflets, suggesting that adsorption proceeds via a rate-limiting structure with negative curvature, in which the hydrophilic face of the phospholipid leaflets is concave. In the studies reported here, we tested whether the surfactant proteins might promote adsorption by inducing lipids to adopt a more negative curvature, closer to the configuration of the hypothetical intermediate. Our experiments used x-ray diffraction to determine how the proteins in their physiological ratio affect the radius of cylindrical monolayers in the negatively curved, inverse hexagonal phase. With binary mixtures of dioleoylphosphatidylethanolamine (DOPE) and dioleoylphosphatidylcholine (DOPC), the proteins produced a dose-related effect on curvature that depended on the phospholipid composition. With DOPE alone, the proteins produced no change. With an increasing mol fraction of DOPC, the response to the proteins increased, reaching a maximum 50% reduction in cylindrical radius at 5% (w/w) protein. This change represented a doubling of curvature at the outer cylindrical surface. The change in spontaneous curvature, defined at approximately the level of the glycerol group, would be greater. Analysis of the results in terms of a Langmuir model for binding to a surface suggests that the effect of the lipids is consistent with a change in the maximum binding capacity. Our findings show that surfactant proteins can promote negative curvature, and support the possibility that they facilitate adsorption by that mechanism. Title: Hydrophobic Surfactant Proteins Strongly Induce Negative Curvature Author: Chavarha, Mariya, Loney, Ryan W., Rananavare, Shankar B., Hall, Stephen B. Year: 2015 The hydrophobic surfactant proteins SP-B and SP-C greatly accelerate the adsorption of vesicles containing the surfactant lipids to form a film that lowers the surface tension of the air/water interface in the lungs. Pulmonary surfactant enters the interface by a process analogous to the fusion of two vesicles. As with fusion, several factors affect adsorption according to how they alter the curvature of lipid leaflets, suggesting that adsorption proceeds via a rate-limiting structure with negative curvature, in which the hydrophilic face of the phospholipid leaflets is concave. In the studies reported here, we tested whether the surfactant proteins might promote adsorption by inducing lipids to adopt a more negative curvature, closer to the configuration of the hypothetical intermediate. Our experiments used x-ray diffraction to determine how the proteins in their physiological ratio affect the radius of cylindrical monolayers in the negatively curved, inverse hexagonal phase. With binary mixtures of dioleoylphosphatidylethanolamine (DOPE) and dioleoylphosphatidylcholine (DOPC), the proteins produced a dose-related effect on curvature that depended on the phospholipid composition. With DOPE alone, the proteins produced no change. With an increasing mol fraction of DOPC, the response to the proteins increased, reaching a maximum 50% reduction in cylindrical radius at 5% (w/w) protein. This change represented a doubling of curvature at the outer cylindrical surface. The change in spontaneous curvature, defined at approximately the level of the glycerol group, would be greater. Analysis of the results in terms of a Langmuir model for binding to a surface suggests that the effect of the lipids is consistent with a change in the maximum binding capacity. Our findings show that surfactant proteins can promote negative curvature, and support the possibility that they facilitate adsorption by that mechanism. Close

• 7. [Article] Minimizing Corrosion of Outdoor Metalworks Using Dispersed Chemically Stabilized Nanoclays in Polyvinylidene Fluoride Latex Coatings

  Nanoclays are small enough to appear optically transparent, yet they have large surface-to-volume and high aspect ratios that can significantly inhibit water diffusion when incorporated into protective ...

  Citation × Citation Citation Abstract Copy Title: Minimizing Corrosion of Outdoor Metalworks Using Dispersed Chemically Stabilized Nanoclays in Polyvinylidene Fluoride Latex Coatings Author: Swartz, Natasja Alexandria, Price, Capri A., Clare, Tami Lasseter Year: 2016 Nanoclays are small enough to appear optically transparent, yet they have large surface-to-volume and high aspect ratios that can significantly inhibit water diffusion when incorporated into protective coatings. Clear coatings, which minimally affect the aesthetics of metalworks, are commonly applied to outdoor metalworks, such as sculptures, to prevent and slow corrosion. In recent years, waterborne clear coatings, rather than solvent-based clear coatings, are increasingly used in many applications to reduce the quantity of volatile organic components in the formulation, yet the performance of dry films produced from waterborne colloidal suspensions is generally poorer. In this work, we aim to improve the barrier properties of a highly weatherable waterborne acrylic/polyvinylidene fluoride emulsion by adding a synthetic nanoclay, Laponite, into the formulation. To improve clay−polymer compatibility, the clay was covalently modified using an acetoxy or perfluoroalkyl silane monomer that is reactive with the hydroxyl groups at the edges of the Laponite platelets. Cation exchange on the clay faces using phosphorylcholine was conducted to increase the stability in water and characterized by zeta potential. Resulting changes in barrier properties of the polymer nanocomposite films were characterized by gravimetry, colorimetry, and electrochemical impedance spectroscopy. Surface ablation after accelerated artificial weathering was monitored by attenuated total internal reflectance Fourier transform infrared microspectroscopy and Raman microspectroscopy, thin film X-ray diffraction (TF-XRD) and gloss and thickness measurements. The composite films showed many improved properties: reduced water sensitivity and ultraviolet-induced polymer degradation, which increased the barrier properties and reduced the diffusion constants over both short- and long-term weathering studies compared with films without nanoclays. The diffusion constant measured for the highest performing composite film showed that the performance gap between relevant water- and solvent-borne coatings used to protect outdoor metals was narrowed by half. Title: Minimizing Corrosion of Outdoor Metalworks Using Dispersed Chemically Stabilized Nanoclays in Polyvinylidene Fluoride Latex Coatings Author: Swartz, Natasja Alexandria, Price, Capri A., Clare, Tami Lasseter Year: 2016 Nanoclays are small enough to appear optically transparent, yet they have large surface-to-volume and high aspect ratios that can significantly inhibit water diffusion when incorporated into protective coatings. Clear coatings, which minimally affect the aesthetics of metalworks, are commonly applied to outdoor metalworks, such as sculptures, to prevent and slow corrosion. In recent years, waterborne clear coatings, rather than solvent-based clear coatings, are increasingly used in many applications to reduce the quantity of volatile organic components in the formulation, yet the performance of dry films produced from waterborne colloidal suspensions is generally poorer. In this work, we aim to improve the barrier properties of a highly weatherable waterborne acrylic/polyvinylidene fluoride emulsion by adding a synthetic nanoclay, Laponite, into the formulation. To improve clay−polymer compatibility, the clay was covalently modified using an acetoxy or perfluoroalkyl silane monomer that is reactive with the hydroxyl groups at the edges of the Laponite platelets. Cation exchange on the clay faces using phosphorylcholine was conducted to increase the stability in water and characterized by zeta potential. Resulting changes in barrier properties of the polymer nanocomposite films were characterized by gravimetry, colorimetry, and electrochemical impedance spectroscopy. Surface ablation after accelerated artificial weathering was monitored by attenuated total internal reflectance Fourier transform infrared microspectroscopy and Raman microspectroscopy, thin film X-ray diffraction (TF-XRD) and gloss and thickness measurements. The composite films showed many improved properties: reduced water sensitivity and ultraviolet-induced polymer degradation, which increased the barrier properties and reduced the diffusion constants over both short- and long-term weathering studies compared with films without nanoclays. The diffusion constant measured for the highest performing composite film showed that the performance gap between relevant water- and solvent-borne coatings used to protect outdoor metals was narrowed by half. Close

• 8. [Article] A Method to Derivatize Surface Silanol Groups to Si-Alkyl Groups in Carbon-Doped Silicon Oxides

  A carbon-doped silicon oxide (CDO) finds use as a material with a low dielectric constant (k) for copper interconnects in multilayered integrated circuits (ICs). Hydrophilic silanol groups (Si–OH) on its ...

  Citation × Citation Citation Abstract Copy Title: A Method to Derivatize Surface Silanol Groups to Si-Alkyl Groups in Carbon-Doped Silicon Oxides Author: Darmakkolla, Srikar Rao, Tran, Hoang, Gupta, Atul, Rananavare, Shankar B. Year: 2016 A carbon-doped silicon oxide (CDO) finds use as a material with a low dielectric constant (k) for copper interconnects in multilayered integrated circuits (ICs). Hydrophilic silanol groups (Si–OH) on its surface, however, can attract moisture, thereby causing an undesirable increase in the dielectric constant. Modification of the exposed hydrophilic surface to a hydrophobic functional group provides one solution to this problem. We report here a strategy for converting surface Si–OH to hydrophobic silicon hydride (Si–H) without affecting the internal oxide network in CDO. The approach involves esterification of the exposed silanol to its triflate (silyltrifluoromethanesulfonate, Si–O–Tf), followed by reduction to Si–H with diisobutylaluminum hydride. Si–H is further modified by a photochemical reaction with an alkene (1-octadecene) to yield Si–R (R = –C18H37) to provide a more moisture resistant, and less polar Si–C as opposed to the Si–O backbone. Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectrometry (XPS), and measurements of the contact angle with water substantiated the successful conversion. The reaction scheme is versatile, transforming silanol groups to silicon hydride in widely varying chemical sites, from small molecules to the surfaces of silica gels, SiOx and CDO wafers. A comparison with the films (self-assembled monolayers) derivatized with the octadecyltrichlorosilane indicated that the new method leads to a thicker (≈5 nm) but more loosely packed hydrocarbon film with slightly lower contact angles. Title: A Method to Derivatize Surface Silanol Groups to Si-Alkyl Groups in Carbon-Doped Silicon Oxides Author: Darmakkolla, Srikar Rao, Tran, Hoang, Gupta, Atul, Rananavare, Shankar B. Year: 2016 A carbon-doped silicon oxide (CDO) finds use as a material with a low dielectric constant (k) for copper interconnects in multilayered integrated circuits (ICs). Hydrophilic silanol groups (Si–OH) on its surface, however, can attract moisture, thereby causing an undesirable increase in the dielectric constant. Modification of the exposed hydrophilic surface to a hydrophobic functional group provides one solution to this problem. We report here a strategy for converting surface Si–OH to hydrophobic silicon hydride (Si–H) without affecting the internal oxide network in CDO. The approach involves esterification of the exposed silanol to its triflate (silyltrifluoromethanesulfonate, Si–O–Tf), followed by reduction to Si–H with diisobutylaluminum hydride. Si–H is further modified by a photochemical reaction with an alkene (1-octadecene) to yield Si–R (R = –C18H37) to provide a more moisture resistant, and less polar Si–C as opposed to the Si–O backbone. Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectrometry (XPS), and measurements of the contact angle with water substantiated the successful conversion. The reaction scheme is versatile, transforming silanol groups to silicon hydride in widely varying chemical sites, from small molecules to the surfaces of silica gels, SiOx and CDO wafers. A comparison with the films (self-assembled monolayers) derivatized with the octadecyltrichlorosilane indicated that the new method leads to a thicker (≈5 nm) but more loosely packed hydrocarbon film with slightly lower contact angles. Close

• 9. [Article] The Biomolecule Sequencer Project: Nanopore Sequencing as a Dual-Use Technology for Crew Health and Astrobiology Investigations

  Human missions to Mars will fundamentally transform how the planet is explored, enabling new scientific discoveries through more sophisticated sample acquisition and processing than can currently be implemented ...

  Citation × Citation Citation Abstract Copy Title: The Biomolecule Sequencer Project: Nanopore Sequencing as a Dual-Use Technology for Crew Health and Astrobiology Investigations Author: John, K. K., Botkin, D. S., Burton, A. S., Castro-Wallace, S. L., Chaput, J. D., Dworkin, J. P., Lehman, Niles, Lupisella, M. L., Mason, C. E., Smith, D. J., Stahl, S., Switzer, C. Year: 2016 Human missions to Mars will fundamentally transform how the planet is explored, enabling new scientific discoveries through more sophisticated sample acquisition and processing than can currently be implemented in robotic exploration. The presence of humans also poses new challenges, including ensuring astronaut safety and health and monitoring contamination. Because the capability to transfer materials to Earth will be extremely limited, there is a strong need for in situ diagnostic capabilities. Nucleotide sequencing is a particularly powerful tool because it can be used to: (1) mitigate microbial risks to crew by allowing identification of microbes in water, in air, and on surfaces; (2) identify optimal treatment strategies for infections that arise in crew members; and (3) track how crew members, microbes, and mission-relevant organisms (e.g., farmed plants) respond to conditions on Mars through transcriptomic and genomic changes. Sequencing would also offer benefits for science investigations occurring on the surface of Mars by permitting identification of Earth-derived contamination in samples. If Mars contains indigenous life, and that life is based on nucleic acids or other closely related molecules, sequencing would serve as a critical tool for the characterization of those molecules. Therefore, spaceflight-compatible nucleic acid sequencing would be an important capability for both crew health and astrobiology exploration. Advances in sequencing technology on Earth have been driven largely by needs for higher throughput and read accuracy. Although some reduction in size has been achieved, nearly all commercially available sequencers are not compatible with spaceflight due to size, power, and operational requirements. Exceptions are nanopore-based sequencers that measure changes in current caused by DNA passing through pores; these devices are inherently much smaller and require significantly less power than sequencers using other detection methods. Consequently, nanopore-based sequencers could be made flight-ready with only minimal modifications. Title: The Biomolecule Sequencer Project: Nanopore Sequencing as a Dual-Use Technology for Crew Health and Astrobiology Investigations Author: John, K. K., Botkin, D. S., Burton, A. S., Castro-Wallace, S. L., Chaput, J. D., Dworkin, J. P., Lehman, Niles, Lupisella, M. L., Mason, C. E., Smith, D. J., Stahl, S., Switzer, C. Year: 2016 Human missions to Mars will fundamentally transform how the planet is explored, enabling new scientific discoveries through more sophisticated sample acquisition and processing than can currently be implemented in robotic exploration. The presence of humans also poses new challenges, including ensuring astronaut safety and health and monitoring contamination. Because the capability to transfer materials to Earth will be extremely limited, there is a strong need for in situ diagnostic capabilities. Nucleotide sequencing is a particularly powerful tool because it can be used to: (1) mitigate microbial risks to crew by allowing identification of microbes in water, in air, and on surfaces; (2) identify optimal treatment strategies for infections that arise in crew members; and (3) track how crew members, microbes, and mission-relevant organisms (e.g., farmed plants) respond to conditions on Mars through transcriptomic and genomic changes. Sequencing would also offer benefits for science investigations occurring on the surface of Mars by permitting identification of Earth-derived contamination in samples. If Mars contains indigenous life, and that life is based on nucleic acids or other closely related molecules, sequencing would serve as a critical tool for the characterization of those molecules. Therefore, spaceflight-compatible nucleic acid sequencing would be an important capability for both crew health and astrobiology exploration. Advances in sequencing technology on Earth have been driven largely by needs for higher throughput and read accuracy. Although some reduction in size has been achieved, nearly all commercially available sequencers are not compatible with spaceflight due to size, power, and operational requirements. Exceptions are nanopore-based sequencers that measure changes in current caused by DNA passing through pores; these devices are inherently much smaller and require significantly less power than sequencers using other detection methods. Consequently, nanopore-based sequencers could be made flight-ready with only minimal modifications. Close

• 10. [Article] Thermal Decomposition of Electronic Cigarette Liquids

  Electronic cigarette liquid (e-liquid) is a solution of propylene glycol and/or glycerol with varying concentrations of nicotine and flavorants. Inhalation of vaporized e-liquid is a method of nicotine ...

  Citation × Citation Citation Abstract Copy Title: Thermal Decomposition of Electronic Cigarette Liquids Author: Jensen, Robert Paul Year: 2016 Electronic cigarette liquid (e-liquid) is a solution of propylene glycol and/or glycerol with varying concentrations of nicotine and flavorants. Inhalation of vaporized e-liquid is a method of nicotine delivery that is growing in popularity and is commonly regarded as safe relative to smoking traditional tobacco products. The thermal decomposition of glycerol and propylene glycol is typical of alcohols and has been investigated, although not exhaustively. In this work, samples of propylene glycol and glycerol were vaporized using an electronic cigarette (e-cigarette) and were analyzed for evidence of decomposition using nuclear magnetic resonance (NMR) spectroscopy. E-cigarettes are shown to degrade glycerol and propylene glycol into a diverse array of oxidation and dehydration products including glyceraldehyde, lactaldehyde, dihydroxyacetone, hydroxyacetone, glycidol, acrolein, propanal, acetone, allyl alcohol, acetic acid, acetaldehyde, formic acid, and formaldehyde. Evidence is presented that the abundance of these decomposition products may depend upon the temperature of the metal heating element but could also depend upon some catalytic aspect of the metal surface. The combination of formaldehyde with alcohols such as glycerol and propylene glycol was explored; hemiformals are stable hemiacetals that can be detected by NMR spectroscopy and are shown to be subject to hydrolysis when diluted in water. Investigations into smoking a glycerol-based tobacco mixture known as shisha using charcoals instead of metal heating elements also resulted in the dehydration of glycerol and sugars. Title: Thermal Decomposition of Electronic Cigarette Liquids Author: Jensen, Robert Paul Year: 2016 Electronic cigarette liquid (e-liquid) is a solution of propylene glycol and/or glycerol with varying concentrations of nicotine and flavorants. Inhalation of vaporized e-liquid is a method of nicotine delivery that is growing in popularity and is commonly regarded as safe relative to smoking traditional tobacco products. The thermal decomposition of glycerol and propylene glycol is typical of alcohols and has been investigated, although not exhaustively. In this work, samples of propylene glycol and glycerol were vaporized using an electronic cigarette (e-cigarette) and were analyzed for evidence of decomposition using nuclear magnetic resonance (NMR) spectroscopy. E-cigarettes are shown to degrade glycerol and propylene glycol into a diverse array of oxidation and dehydration products including glyceraldehyde, lactaldehyde, dihydroxyacetone, hydroxyacetone, glycidol, acrolein, propanal, acetone, allyl alcohol, acetic acid, acetaldehyde, formic acid, and formaldehyde. Evidence is presented that the abundance of these decomposition products may depend upon the temperature of the metal heating element but could also depend upon some catalytic aspect of the metal surface. The combination of formaldehyde with alcohols such as glycerol and propylene glycol was explored; hemiformals are stable hemiacetals that can be detected by NMR spectroscopy and are shown to be subject to hydrolysis when diluted in water. Investigations into smoking a glycerol-based tobacco mixture known as shisha using charcoals instead of metal heating elements also resulted in the dehydration of glycerol and sugars. Close