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• 1. [Article] Transport of ozone across an air/water interface coupled with aqueous decomposition

  Photoacoustic spectroscopy was used to analyze the transport of ozone through the air/water interface. Experimental results showed that the ozone transport rate is similar to rates measured for other gases ...

  Citation × Citation Citation Abstract Copy Title: Transport of ozone across an air/water interface coupled with aqueous decomposition Author: Mehrabzadeh, Ahmad Ali Year: 1980 Photoacoustic spectroscopy was used to analyze the transport of ozone through the air/water interface. Experimental results showed that the ozone transport rate is similar to rates measured for other gases of low solubility and low reactivity. The transport rate increases with increasing pH. The decomposition rate of ozone was studied in solutions. The decomposition rate also depends on the pH of the solution, and in high pHs both the deposition velocity and the decomposition rate constant of ozone have larger values. The value of the deposition velocity (Kd) is 3.7 ± .9 x 10-3 cm/sec and the decomposition rate constant is 5.3 ± 0.6 x 10-5 sec-l for distilled water. For ocean water, the respective values are 5.2 ± 0.4 x 10-3 sec-l and 7.8 ± 0.4 x 10-4 cm/sec respectively. Title: Transport of ozone across an air/water interface coupled with aqueous decomposition Author: Mehrabzadeh, Ahmad Ali Year: 1980 Photoacoustic spectroscopy was used to analyze the transport of ozone through the air/water interface. Experimental results showed that the ozone transport rate is similar to rates measured for other gases of low solubility and low reactivity. The transport rate increases with increasing pH. The decomposition rate of ozone was studied in solutions. The decomposition rate also depends on the pH of the solution, and in high pHs both the deposition velocity and the decomposition rate constant of ozone have larger values. The value of the deposition velocity (Kd) is 3.7 ± .9 x 10-3 cm/sec and the decomposition rate constant is 5.3 ± 0.6 x 10-5 sec-l for distilled water. For ocean water, the respective values are 5.2 ± 0.4 x 10-3 sec-l and 7.8 ± 0.4 x 10-4 cm/sec respectively. Close

• 2. [Article] Rational Design of Materials for the Protection of Outdoor Metalworks

  Protective coatings are commonly used to protect culturally significant works, such as outdoor sculptures and architectural elements. Given the valuable nature of such metalworks, there is a surprising ...

  Citation × Citation Citation Abstract Copy Title: Rational Design of Materials for the Protection of Outdoor Metalworks Author: Swartz, Natasja Alexandria Year: 2015 Protective coatings are commonly used to protect culturally significant works, such as outdoor sculptures and architectural elements. Given the valuable nature of such metalworks, there is a surprising lack of environmentally sustainable coatings available for their conservation. High performance clear coatings are not developed or thoroughly tested for compatibility and longevity on outdoor sculptures. This can make the implementation of both methods and materials, no matter how promising in a lab, a significant hurdle for the conservation science community. This dissertation work initially aims to replace high-VOC formulations such as acrylic lacquers and waxes currently used as protective coatings for bronze with a waterborne coating by investigating the film formation differences between coating types. Such differences likely have implications for initial film barrier properties as well as long-term performance. For coating any large-scale metal object, cost-effectiveness limits applicable coatings to commercially available resins with some minor adjustments. Additional requirements for protective coatings for artwork require they must also be transparent, reversible, easily applied and environmentally sustainable. The chemical and physical properties of polymeric coatings with nanoclays modifiers were investigated as they may offer superior weatherability and act as better barriers to water absorption than commonly used lacquers and waxes. This work ultimately finds that nanocomposites with poly(vinylidene fluoride) latex and chemically stabilized nanoclays significantly improved performance and may be a viable option in the protection of material cultural heritage. Protection of high value objects where aesthetics is also important, such as airplanes, buildings, and sculptures are among the possible applications for this research. Title: Rational Design of Materials for the Protection of Outdoor Metalworks Author: Swartz, Natasja Alexandria Year: 2015 Protective coatings are commonly used to protect culturally significant works, such as outdoor sculptures and architectural elements. Given the valuable nature of such metalworks, there is a surprising lack of environmentally sustainable coatings available for their conservation. High performance clear coatings are not developed or thoroughly tested for compatibility and longevity on outdoor sculptures. This can make the implementation of both methods and materials, no matter how promising in a lab, a significant hurdle for the conservation science community. This dissertation work initially aims to replace high-VOC formulations such as acrylic lacquers and waxes currently used as protective coatings for bronze with a waterborne coating by investigating the film formation differences between coating types. Such differences likely have implications for initial film barrier properties as well as long-term performance. For coating any large-scale metal object, cost-effectiveness limits applicable coatings to commercially available resins with some minor adjustments. Additional requirements for protective coatings for artwork require they must also be transparent, reversible, easily applied and environmentally sustainable. The chemical and physical properties of polymeric coatings with nanoclays modifiers were investigated as they may offer superior weatherability and act as better barriers to water absorption than commonly used lacquers and waxes. This work ultimately finds that nanocomposites with poly(vinylidene fluoride) latex and chemically stabilized nanoclays significantly improved performance and may be a viable option in the protection of material cultural heritage. Protection of high value objects where aesthetics is also important, such as airplanes, buildings, and sculptures are among the possible applications for this research. Close

• 3. [Article] Quasispecies-Like Behavior Observed in Catalytic RNA Populations Evolving in a Test Tube

  Background: During the RNA World, molecular populations were probably very small and highly susceptible to the force of strong random drift. In conjunction with Muller's Ratchet, this would have imposed ...

  Citation × Citation Citation Abstract Copy Title: Quasispecies-Like Behavior Observed in Catalytic RNA Populations Evolving in a Test Tube Author: Diaz Arenas, Carolina, Lehman, Niles Year: 2010 Background: During the RNA World, molecular populations were probably very small and highly susceptible to the force of strong random drift. In conjunction with Muller's Ratchet, this would have imposed difficulties for the preservation of the genetic information and the survival of the populations. Mechanisms that allowed these nascent populations to overcome this problem must have been advantageous. Results: Using continuous in vitro evolution experimentation with an increased mutation rate imposed by MnCl2, it was found that clonal 100-molecule populations of ribozymes clearly exhibit certain characteristics of a quasispecies. This is the first time this has been seen with a catalytic RNA. Extensive genotypic sampling from two replicate lineages was gathered and phylogenetic networks were constructed to elucidate the structure of the evolving RNA populations. A common distribution was found in which a mutant sequence was present at high frequency, surrounded by a cloud of mutant with lower frequencies. This is a typical distribution of quasispecies. Most of the mutants in these clouds were connected by short Hamming distance values, indicating their close relatedness. Conclusions: The quasispecies nature of mutant RNA clouds facilitates the recovery of genotypes under pressure of being removed from the population by random drift. The empirical populations therefore evolved a genotypic resiliency despite a high mutation rate by adopting the characteristics of quasispecies, implying that primordial RNA pools could have used this strategy to avoid extinction. Title: Quasispecies-Like Behavior Observed in Catalytic RNA Populations Evolving in a Test Tube Author: Diaz Arenas, Carolina, Lehman, Niles Year: 2010 Background: During the RNA World, molecular populations were probably very small and highly susceptible to the force of strong random drift. In conjunction with Muller's Ratchet, this would have imposed difficulties for the preservation of the genetic information and the survival of the populations. Mechanisms that allowed these nascent populations to overcome this problem must have been advantageous. Results: Using continuous in vitro evolution experimentation with an increased mutation rate imposed by MnCl2, it was found that clonal 100-molecule populations of ribozymes clearly exhibit certain characteristics of a quasispecies. This is the first time this has been seen with a catalytic RNA. Extensive genotypic sampling from two replicate lineages was gathered and phylogenetic networks were constructed to elucidate the structure of the evolving RNA populations. A common distribution was found in which a mutant sequence was present at high frequency, surrounded by a cloud of mutant with lower frequencies. This is a typical distribution of quasispecies. Most of the mutants in these clouds were connected by short Hamming distance values, indicating their close relatedness. Conclusions: The quasispecies nature of mutant RNA clouds facilitates the recovery of genotypes under pressure of being removed from the population by random drift. The empirical populations therefore evolved a genotypic resiliency despite a high mutation rate by adopting the characteristics of quasispecies, implying that primordial RNA pools could have used this strategy to avoid extinction. Close

• 4. [Article] Molecular View Modeling of Atmospheric Organic Particulate Matter: Incorporating Molecular Structure and Co-Condensation of Water

  Most urban and regional models used to predict levels of organic particulate matter (OPM) are based on fundamental equations for gas/particle partitioning, but make the highly simplifying, anonymized-view ...

  Citation × Citation Citation Abstract Copy Title: Molecular View Modeling of Atmospheric Organic Particulate Matter: Incorporating Molecular Structure and Co-Condensation of Water Author: Pankow, James F., Marks, Marguerite Colasurdo, Barsanti, Kelley C., Mahmud, Abdullah, Asher, William E., Li, Jingyi, Ying, Qi, Jathar, Shantanu H., Kleeman, Michael J. Year: 2015 Most urban and regional models used to predict levels of organic particulate matter (OPM) are based on fundamental equations for gas/particle partitioning, but make the highly simplifying, anonymized-view (AV) assumptions that OPM levels are not affected by either: a) the molecular. characteristics of the condensing organic compounds (other than simple volatility); or b) co-condensation of water as driven by non-zero relative humidity (RH) values. The simplifying assumptions have allowed parameterized chamber results for formation of secondary organic aerosol (SOA) (e.g., “two-product” (2p) coefficients) to be incorporated in chemical transport models. However, a return towards a less simplistic (and more computationally demanding) molecular view (MV) is needed that acknowledges that atmospheric OPM is a mixture of organic compounds with differing polarities, water, and in some cases dissolved salts. The higher computational cost of MV modeling results from a need for iterative calculations of the composition-dependent gas/particle partition coefficient values. MV modeling of OPM that considered water uptake (but not dissolved salts) was carried out for the southeast United States for the period August 29 through September 7, 2006. Three model variants were used at three universities: CMAQ-RH-2p (at PSU), UCD/CIT-RH-2p (at UCD), and CMAQ-RH-MCM (at TAMU). With the first two, MV structural characteristics (carbon number and numbers of functional groups) were assigned to each of the 2p products used in CMAQv.4.7.1 such that resulting predicted Kp,i values matched those in CMAQv.4.7.1. When water uptake was allowed, most runs assumed that uptake occurred only into the SOA portion, and imposed immiscibility of SOA with primary organic aerosol (POA). (POA is often viewed as rather non-polar, while SOA is commonly viewed as moderately-to-rather polar. Some runs with UCD/CIT-RH-2p were used to investigate the effects of POA/SOA miscibility.) CMAQ-RH-MCM used MCM to generate oxidation products, and assumed miscibility of SOA and POA. In a ∼500 km wide band from Louisiana through to at least North Carolina, CMAQ-RH-2p and UCD/CIT-RH-2p predicted that water uptake can increase SOA levels by as much as 50 to 100% (from a range of ∼1 to 2 μg m-3 to a range of ∼1 to 4 μg m-3). CMAQ-RH-MCM predicted much lower effects of water uptake on SOA levels (<10% increase). The results from CMAQ-RH-2p and UCD/CIT-RH-2p are considered more reflective of reality. In the Alabama/Georgia hotspot, both CMAQ-RH-2p and UCD/CIT-RH-2p predicted aerosol water levels that are up to nearly half the predicted SOA levels, namely ∼0.5 to 2 μg m-3. Such water levels in SOA will affect particle optical properties, viscosity, gas/particle partitioning times, and rates of hydrolysis and water elimination reactions. Title: Molecular View Modeling of Atmospheric Organic Particulate Matter: Incorporating Molecular Structure and Co-Condensation of Water Author: Pankow, James F., Marks, Marguerite Colasurdo, Barsanti, Kelley C., Mahmud, Abdullah, Asher, William E., Li, Jingyi, Ying, Qi, Jathar, Shantanu H., Kleeman, Michael J. Year: 2015 Most urban and regional models used to predict levels of organic particulate matter (OPM) are based on fundamental equations for gas/particle partitioning, but make the highly simplifying, anonymized-view (AV) assumptions that OPM levels are not affected by either: a) the molecular. characteristics of the condensing organic compounds (other than simple volatility); or b) co-condensation of water as driven by non-zero relative humidity (RH) values. The simplifying assumptions have allowed parameterized chamber results for formation of secondary organic aerosol (SOA) (e.g., “two-product” (2p) coefficients) to be incorporated in chemical transport models. However, a return towards a less simplistic (and more computationally demanding) molecular view (MV) is needed that acknowledges that atmospheric OPM is a mixture of organic compounds with differing polarities, water, and in some cases dissolved salts. The higher computational cost of MV modeling results from a need for iterative calculations of the composition-dependent gas/particle partition coefficient values. MV modeling of OPM that considered water uptake (but not dissolved salts) was carried out for the southeast United States for the period August 29 through September 7, 2006. Three model variants were used at three universities: CMAQ-RH-2p (at PSU), UCD/CIT-RH-2p (at UCD), and CMAQ-RH-MCM (at TAMU). With the first two, MV structural characteristics (carbon number and numbers of functional groups) were assigned to each of the 2p products used in CMAQv.4.7.1 such that resulting predicted Kp,i values matched those in CMAQv.4.7.1. When water uptake was allowed, most runs assumed that uptake occurred only into the SOA portion, and imposed immiscibility of SOA with primary organic aerosol (POA). (POA is often viewed as rather non-polar, while SOA is commonly viewed as moderately-to-rather polar. Some runs with UCD/CIT-RH-2p were used to investigate the effects of POA/SOA miscibility.) CMAQ-RH-MCM used MCM to generate oxidation products, and assumed miscibility of SOA and POA. In a ∼500 km wide band from Louisiana through to at least North Carolina, CMAQ-RH-2p and UCD/CIT-RH-2p predicted that water uptake can increase SOA levels by as much as 50 to 100% (from a range of ∼1 to 2 μg m-3 to a range of ∼1 to 4 μg m-3). CMAQ-RH-MCM predicted much lower effects of water uptake on SOA levels (<10% increase). The results from CMAQ-RH-2p and UCD/CIT-RH-2p are considered more reflective of reality. In the Alabama/Georgia hotspot, both CMAQ-RH-2p and UCD/CIT-RH-2p predicted aerosol water levels that are up to nearly half the predicted SOA levels, namely ∼0.5 to 2 μg m-3. Such water levels in SOA will affect particle optical properties, viscosity, gas/particle partitioning times, and rates of hydrolysis and water elimination reactions. Close

• 5. [Article] Study of photolytic interference on HO measurements by LIF-FAGE

  For many years there has been a great interest among the scientific community in the study of the hydroxyl radical, HO. This interest stems from the fundamental role played by this molecule in the photochemistry ...

  Citation × Citation Citation Abstract Copy Title: Study of photolytic interference on HO measurements by LIF-FAGE Author: Martinez, Carmen Ivette Year: 1989 For many years there has been a great interest among the scientific community in the study of the hydroxyl radical, HO. This interest stems from the fundamental role played by this molecule in the photochemistry of the atmosphere, mainly as a cleansing agent of environmental pollutants. Knowing the concentration of the radical would enable scientists to corroborate current atmospheric models and to predict future trends in the atmosphere. Even though there is a great interest in the determination of atmospheric concentrations of this molecule, the task has been very difficult. This is mainly due to the lack of a method sensitive enough to detect concentrations around 106 molecules per cubic centimeter. The most accurate method presently available is the method of laser induced fluorescence using the fluorescence assay with gas expansion technique (LIF-FAGE). This method involves low pressure excitation of HO from its ground state to its lowest electronic excited state and observing the consequent fluorescence around 309 nm. The procedure is done at a pressure of 5 Torr to maximize the fluorescence lifetime of the radical and to minimize the interference of photolytic species. Background determination is achieved by chemical modulation using isobutane in a second channel of the same cell which removes the HO signal. In this study an assessment of the level of ozone interference in LIFF AGE has been done by calculating the relative population distribution of HO among its rotational levels and from this, determining its temperature. When the laser passes through the excitation detection cell it photolyses the ozone present producing in this way the highly reactive 0 1(D). When this molecule reacts with water or with isobutane it produces HO, and this is the source of interference in the actual measurements. In the determination of the relative population distributions of the different HO species, it was found that the naturally occurring HO has a thermal distribution with a temperature of about 300 K. The HO molecules produced from the reaction of 0 1(D) with isobutane also showed a thermal distribution with a temperature of about 230 K. On the other hand, the HO produced from the reaction of 0 1(D) with water did not show a thermal distribution. Two distinct temperatures were observed for this case: one around 200 K for values of K = 1 to 4, and the second one around 3000 K for values of K = 5 to 6. These values agree with previous experimental results for LIF methods by other authors except for the fact that the deviation from the first temperature determined by other authors starts at K = 6 or 7. Title: Study of photolytic interference on HO measurements by LIF-FAGE Author: Martinez, Carmen Ivette Year: 1989 For many years there has been a great interest among the scientific community in the study of the hydroxyl radical, HO. This interest stems from the fundamental role played by this molecule in the photochemistry of the atmosphere, mainly as a cleansing agent of environmental pollutants. Knowing the concentration of the radical would enable scientists to corroborate current atmospheric models and to predict future trends in the atmosphere. Even though there is a great interest in the determination of atmospheric concentrations of this molecule, the task has been very difficult. This is mainly due to the lack of a method sensitive enough to detect concentrations around 106 molecules per cubic centimeter. The most accurate method presently available is the method of laser induced fluorescence using the fluorescence assay with gas expansion technique (LIF-FAGE). This method involves low pressure excitation of HO from its ground state to its lowest electronic excited state and observing the consequent fluorescence around 309 nm. The procedure is done at a pressure of 5 Torr to maximize the fluorescence lifetime of the radical and to minimize the interference of photolytic species. Background determination is achieved by chemical modulation using isobutane in a second channel of the same cell which removes the HO signal. In this study an assessment of the level of ozone interference in LIFF AGE has been done by calculating the relative population distribution of HO among its rotational levels and from this, determining its temperature. When the laser passes through the excitation detection cell it photolyses the ozone present producing in this way the highly reactive 0 1(D). When this molecule reacts with water or with isobutane it produces HO, and this is the source of interference in the actual measurements. In the determination of the relative population distributions of the different HO species, it was found that the naturally occurring HO has a thermal distribution with a temperature of about 300 K. The HO molecules produced from the reaction of 0 1(D) with isobutane also showed a thermal distribution with a temperature of about 230 K. On the other hand, the HO produced from the reaction of 0 1(D) with water did not show a thermal distribution. Two distinct temperatures were observed for this case: one around 200 K for values of K = 1 to 4, and the second one around 3000 K for values of K = 5 to 6. These values agree with previous experimental results for LIF methods by other authors except for the fact that the deviation from the first temperature determined by other authors starts at K = 6 or 7. Close

• 6. [Article] Investigations of Electronic Cigarette Chemistry: 1. Formation Pathways for Degradation Products using Isotopic Labeling; and 2. Gas/Particle Partitioning of Nicotine and Flavor Related Chemicals in Electronic Cigarette Fluids

  Use of electronic cigarettes (e-cigarettes) is rapidly growing around the world. E-cigarettes are commonly used as an alternative nicotine delivery system, and have been advocated as generating lower levels ...

  Citation × Citation Citation Abstract Copy Title: Investigations of Electronic Cigarette Chemistry: 1. Formation Pathways for Degradation Products using Isotopic Labeling; and 2. Gas/Particle Partitioning of Nicotine and Flavor Related Chemicals in Electronic Cigarette Fluids Author: Kim, Kilsun Year: 2017 Use of electronic cigarettes (e-cigarettes) is rapidly growing around the world. E-cigarettes are commonly used as an alternative nicotine delivery system, and have been advocated as generating lower levels of harmful chemicals compared to conventional cigarettes. Cigarette smoke-like aerosols are generated when e-cigarettes heat e-liquids. The main components of e-cigarette liquids are propylene glycol (PG) and glycerol (GL) in a varying ratio, plus nicotine and flavor chemicals. Both PG and GL are considered safe to ingest in foods and beverages, but the toxicity of these chemicals in aerosols is unknown. Current studies of e-cigarettes have mainly focused on dehydration and oxidation products of PG and GL. In this study, the other degradation products that can be generated during the vaping process are discussed. In addition, the gas/particle partitioning of chemicals in vaping aerosols is determined. This work finds that the formation of benzene in electronic cigarettes depends on the wattage, types of coils, and devices. To simulate commerical e-cigarette liquids, mixtures containing equal parts of PG and GL by volume were made with the following added components: benzoic acid (BA), benzoic acid with nicotine (Nic), benzaldehyde (BZ), band enzaldehyde with nicotine. PG only, GL only, and PG and GL mixtures were also made for comparison. The data presented here demonstrate that more benzene is generated as the wattage of a device increases. The results also seem to support the importance of ventilation in the generation of benzene. More benzene is generated from the mixtures containing benzoic acid when using the EVOD device with a smaller vent. However, benzaldehyde yields more benzene when using the Subtank Nano device with a larger vent. Findings also indicate that more benzene is produced from GL rather than PG. This thesis also addresses the chemical formation pathways of degradation compounds found in the aerosols formed from isotopically labeled e-cigarette liquids. Mixtures of both 13C-labeled and unlabeled PG as well as GL were made. The mixtures were vaped and gas-phase samples were collected to determine which chemicals were in the gas-phase portion of the aerosols. With the use of GC/MS methods, these isotopic labeling experiments provided evidence that the majority of the benzene, acetaldehyde, 2,3-butanedione, toluene, xylene, acrolein, and furan found in e-cigarette aerosols originates from GL in the PG plus GL mixtures. It was also shown that the majority of propanal is derived from PG: while hydroxyacetone can be formed from both PG and GL. Possible mechanisms for the formation of acetaldehyde, benzene, 2,3-butanedione, toluene, and xylene formation are proposed. Last, this study investigated the gas/particle partitioning of nicotine and flavor-related chemicals in e-cigarette fluids. The gas/particle partitioning behavior of chemicals in e-cigarettes fluids is highly dependent on the chemical volatility. A total of 37 compounds were examined. The target compounds were divided into 3 groups based on their vapor pressures: high, medium, and low. Headspace gas samples were collected and analyzed to determine the concentration of a compound in equilibrium with the liquid phase. The gas and liquid concentrations were used to calculate the gas/particle partitioning constant (Kp) for each compound. In an e-cigarette aerosol, volatile compounds have smaller Kp values and tend to be found in greater proportion in the gas-phase, whereas the less volatile compounds are likely to stay in the particle phase. General agreement with theory was found for compounds with known activity coefficients in PG and GL, indicating that theory can be used to predict Kp values for other compounds. Title: Investigations of Electronic Cigarette Chemistry: 1. Formation Pathways for Degradation Products using Isotopic Labeling; and 2. Gas/Particle Partitioning of Nicotine and Flavor Related Chemicals in Electronic Cigarette Fluids Author: Kim, Kilsun Year: 2017 Use of electronic cigarettes (e-cigarettes) is rapidly growing around the world. E-cigarettes are commonly used as an alternative nicotine delivery system, and have been advocated as generating lower levels of harmful chemicals compared to conventional cigarettes. Cigarette smoke-like aerosols are generated when e-cigarettes heat e-liquids. The main components of e-cigarette liquids are propylene glycol (PG) and glycerol (GL) in a varying ratio, plus nicotine and flavor chemicals. Both PG and GL are considered safe to ingest in foods and beverages, but the toxicity of these chemicals in aerosols is unknown. Current studies of e-cigarettes have mainly focused on dehydration and oxidation products of PG and GL. In this study, the other degradation products that can be generated during the vaping process are discussed. In addition, the gas/particle partitioning of chemicals in vaping aerosols is determined. This work finds that the formation of benzene in electronic cigarettes depends on the wattage, types of coils, and devices. To simulate commerical e-cigarette liquids, mixtures containing equal parts of PG and GL by volume were made with the following added components: benzoic acid (BA), benzoic acid with nicotine (Nic), benzaldehyde (BZ), band enzaldehyde with nicotine. PG only, GL only, and PG and GL mixtures were also made for comparison. The data presented here demonstrate that more benzene is generated as the wattage of a device increases. The results also seem to support the importance of ventilation in the generation of benzene. More benzene is generated from the mixtures containing benzoic acid when using the EVOD device with a smaller vent. However, benzaldehyde yields more benzene when using the Subtank Nano device with a larger vent. Findings also indicate that more benzene is produced from GL rather than PG. This thesis also addresses the chemical formation pathways of degradation compounds found in the aerosols formed from isotopically labeled e-cigarette liquids. Mixtures of both 13C-labeled and unlabeled PG as well as GL were made. The mixtures were vaped and gas-phase samples were collected to determine which chemicals were in the gas-phase portion of the aerosols. With the use of GC/MS methods, these isotopic labeling experiments provided evidence that the majority of the benzene, acetaldehyde, 2,3-butanedione, toluene, xylene, acrolein, and furan found in e-cigarette aerosols originates from GL in the PG plus GL mixtures. It was also shown that the majority of propanal is derived from PG: while hydroxyacetone can be formed from both PG and GL. Possible mechanisms for the formation of acetaldehyde, benzene, 2,3-butanedione, toluene, and xylene formation are proposed. Last, this study investigated the gas/particle partitioning of nicotine and flavor-related chemicals in e-cigarette fluids. The gas/particle partitioning behavior of chemicals in e-cigarettes fluids is highly dependent on the chemical volatility. A total of 37 compounds were examined. The target compounds were divided into 3 groups based on their vapor pressures: high, medium, and low. Headspace gas samples were collected and analyzed to determine the concentration of a compound in equilibrium with the liquid phase. The gas and liquid concentrations were used to calculate the gas/particle partitioning constant (Kp) for each compound. In an e-cigarette aerosol, volatile compounds have smaller Kp values and tend to be found in greater proportion in the gas-phase, whereas the less volatile compounds are likely to stay in the particle phase. General agreement with theory was found for compounds with known activity coefficients in PG and GL, indicating that theory can be used to predict Kp values for other compounds. Close

• 7. [Article] Iron(III)-Salophene: An Organometallic Compound with Selective Cytotoxic and Anti-Proliferative Properties in Platinum-Resistant Ovarian Cancer Cells

  Background: In this pioneer study to the biological activity of organometallic compound Iron(III)-salophene (Fe-SP) the specific effects of Fe-SP on viability, morphology, proliferation, and cell-cycle ...

  Citation × Citation Citation Abstract Copy Title: Iron(III)-Salophene: An Organometallic Compound with Selective Cytotoxic and Anti-Proliferative Properties in Platinum-Resistant Ovarian Cancer Cells Author: Lange, Thilo S., Kim, Kyu Kwang, Singh, Rakesh K., Strongin, Robert M., McCourt, Carolyn, Brard, Laurent Year: 2008 Background: In this pioneer study to the biological activity of organometallic compound Iron(III)-salophene (Fe-SP) the specific effects of Fe-SP on viability, morphology, proliferation, and cell-cycle progression on platinum-resistant ovariancancer cell lines were investigated. Methodology/Principal Findings: Fe-SP displayed selective cytotoxicity against SKOV-3 and OVCAR-3 (ovarian epithelial adenocarcinoma) cell lines at concentrations between 100 nM and 1 μM, while the viability of HeLa cells (epithelial cervix adenocarcinoma) or primary lung or skin fibroblasts was not affected. SKOV-3 cells in contrast to fibroblasts after treatment with Fe-SP revealed apparent hallmarks of apoptosis including densely stained nuclear granular bodies within fragmented nuclei, highly condensed chromatin and chromatin fragmentation. Fe-SP treatment led to the activation of markers of the extrinsic (Caspase-8) and intrinsic (Caspase-9) pathway of apoptosis as well as of executioner Caspase-3 while PARP-1 was deactivated. Fe-SP exerted effects as an anti-proliferative agent with an IC50 value of 300 nM and caused delayed progression of cells through S-phase phase of the cell cycle resulting in a complete S-phase arrest. When intra-peritoneally applied to rats Fe-SP did not show any systemic toxicity at concentrations that in preliminary trials were determined to be chemotherapeutic relevant doses in a rat ovarian cancer cell model. Conclusion/Significance: The present report suggests that Fe-SP is a potent growth-suppressing agent in vitro for cell lines derived from ovarian cancer and a potential therapeutic drug to treat such tumors in vivo Title: Iron(III)-Salophene: An Organometallic Compound with Selective Cytotoxic and Anti-Proliferative Properties in Platinum-Resistant Ovarian Cancer Cells Author: Lange, Thilo S., Kim, Kyu Kwang, Singh, Rakesh K., Strongin, Robert M., McCourt, Carolyn, Brard, Laurent Year: 2008 Background: In this pioneer study to the biological activity of organometallic compound Iron(III)-salophene (Fe-SP) the specific effects of Fe-SP on viability, morphology, proliferation, and cell-cycle progression on platinum-resistant ovariancancer cell lines were investigated. Methodology/Principal Findings: Fe-SP displayed selective cytotoxicity against SKOV-3 and OVCAR-3 (ovarian epithelial adenocarcinoma) cell lines at concentrations between 100 nM and 1 μM, while the viability of HeLa cells (epithelial cervix adenocarcinoma) or primary lung or skin fibroblasts was not affected. SKOV-3 cells in contrast to fibroblasts after treatment with Fe-SP revealed apparent hallmarks of apoptosis including densely stained nuclear granular bodies within fragmented nuclei, highly condensed chromatin and chromatin fragmentation. Fe-SP treatment led to the activation of markers of the extrinsic (Caspase-8) and intrinsic (Caspase-9) pathway of apoptosis as well as of executioner Caspase-3 while PARP-1 was deactivated. Fe-SP exerted effects as an anti-proliferative agent with an IC50 value of 300 nM and caused delayed progression of cells through S-phase phase of the cell cycle resulting in a complete S-phase arrest. When intra-peritoneally applied to rats Fe-SP did not show any systemic toxicity at concentrations that in preliminary trials were determined to be chemotherapeutic relevant doses in a rat ovarian cancer cell model. Conclusion/Significance: The present report suggests that Fe-SP is a potent growth-suppressing agent in vitro for cell lines derived from ovarian cancer and a potential therapeutic drug to treat such tumors in vivo Close

• 8. [Article] Copper Nanowires Synthesis and Self-Assembly for Interconnect Applications

  One-dimensional (1D) nanomaterial self-assembly offers an excellent approach to the fabrication of highly complex nanodevices. Despite considerable effort and research, precisely controlling the orientation ...

  Citation × Citation Citation Abstract Copy Title: Copper Nanowires Synthesis and Self-Assembly for Interconnect Applications Author: Darmakkolla, Srikar Rao Year: 2017 One-dimensional (1D) nanomaterial self-assembly offers an excellent approach to the fabrication of highly complex nanodevices. Despite considerable effort and research, precisely controlling the orientation and positioning of nanowires (NWs) on a large-scale area and assembling into a functional device is still a state of the art problem. This thesis focuses on the dimensionally controlled copper nanowires (Cu NWs) synthesis, and magnetic field assisted self-assembly of cupronickel nanowires (Cu/Ni NWs) into interconnect structures on a carbon doped silicon dioxide (CDO) wafer. CDO is a low dielectric constant (k) material used for copper interconnects in multilayered complex integrated circuits (ICs). Here, a strong affinity of copper (Cu) and nickel (Ni) to thiol (-SH) functional groups were exploited to strongly adhere the nanowires (Cu/Ni NWs) onto the CDO substrate. Thiol (-SH) functionalization of the CDO surface was achieved via a series of reactions involving (1) esterification of the surface exposed ≡Si-OH functional group to its triflate (≡Si-O-Tf), (2) reduction of triflate to ≡Si-H using DIBAL-H, and (3) hydrosilylation of ≡Si-H using 2-propene thiol (≡Si-(CH2)3-SH) in a photochemical reaction. The thiol functionalization of CDO surface enhances the interaction of Cu/Ni NWs with strong chemical bonds. The same reaction scheme was also used in the functionalization of the hydrophilic (Si-OH) surface to the hydrophobic long alkyl chain derivatized (≡Si-CH2-(CH2)16-CH3) surface. This long alkyl chain modified surface acts as an excellent moisture resistant film, which helps to maintain the low-k value of CDO. The dimensionally controlled Cu NWs were synthesized by a wet chemical approach. Optimization of the reducing agent, hydrazine (N2H4), controlled the surface morphology of nanowires (NWs). Interestingly, the high concentration of reducing agent produced particle decorated and/or with a rough NW surface, and conversely decreasing its concentration resulted in a comparatively thin, particle-free and smooth surface. The reaction temperature affected the aspect ratio (Length/Diameter) of the NWs. As the reaction temperature increased from 60 to 90 °C, the aspect ratio decreased from 140 to 21. Controlling the orientation of Cu NWs in a magnetic field was accomplished by coating them with a thin layer (~20 nm) of ferromagnetic nickel (Ni). This Ni-coated NWs showed an excellent degree of alignment (half-width ≈10 degrees) in the direction of an applied magnetic field over a large surface area at field strength as low as 2500 Gauss. Also, the Ni coating helped in protecting the copper core from oxidation resulting in better electrical wire-to-wire contacts. A nanowire-based interconnect channel was fabricated by combining magnetic field assisted alignment and deposition of aligned NWs on a thiol-modified and photolithography patterned CDO substrate. The NWs, deposited in the trenches, strongly bonded to the thiol-derivatized CDO substrate while an acetone wash removed loosely bound NWs on the photoresist surface. In electrical characterization, the directionally well-aligned Cu/Ni NWs channel displayed surprisingly two-fold higher conductivity than randomly arranged NWs channel. Title: Copper Nanowires Synthesis and Self-Assembly for Interconnect Applications Author: Darmakkolla, Srikar Rao Year: 2017 One-dimensional (1D) nanomaterial self-assembly offers an excellent approach to the fabrication of highly complex nanodevices. Despite considerable effort and research, precisely controlling the orientation and positioning of nanowires (NWs) on a large-scale area and assembling into a functional device is still a state of the art problem. This thesis focuses on the dimensionally controlled copper nanowires (Cu NWs) synthesis, and magnetic field assisted self-assembly of cupronickel nanowires (Cu/Ni NWs) into interconnect structures on a carbon doped silicon dioxide (CDO) wafer. CDO is a low dielectric constant (k) material used for copper interconnects in multilayered complex integrated circuits (ICs). Here, a strong affinity of copper (Cu) and nickel (Ni) to thiol (-SH) functional groups were exploited to strongly adhere the nanowires (Cu/Ni NWs) onto the CDO substrate. Thiol (-SH) functionalization of the CDO surface was achieved via a series of reactions involving (1) esterification of the surface exposed ≡Si-OH functional group to its triflate (≡Si-O-Tf), (2) reduction of triflate to ≡Si-H using DIBAL-H, and (3) hydrosilylation of ≡Si-H using 2-propene thiol (≡Si-(CH2)3-SH) in a photochemical reaction. The thiol functionalization of CDO surface enhances the interaction of Cu/Ni NWs with strong chemical bonds. The same reaction scheme was also used in the functionalization of the hydrophilic (Si-OH) surface to the hydrophobic long alkyl chain derivatized (≡Si-CH2-(CH2)16-CH3) surface. This long alkyl chain modified surface acts as an excellent moisture resistant film, which helps to maintain the low-k value of CDO. The dimensionally controlled Cu NWs were synthesized by a wet chemical approach. Optimization of the reducing agent, hydrazine (N2H4), controlled the surface morphology of nanowires (NWs). Interestingly, the high concentration of reducing agent produced particle decorated and/or with a rough NW surface, and conversely decreasing its concentration resulted in a comparatively thin, particle-free and smooth surface. The reaction temperature affected the aspect ratio (Length/Diameter) of the NWs. As the reaction temperature increased from 60 to 90 °C, the aspect ratio decreased from 140 to 21. Controlling the orientation of Cu NWs in a magnetic field was accomplished by coating them with a thin layer (~20 nm) of ferromagnetic nickel (Ni). This Ni-coated NWs showed an excellent degree of alignment (half-width ≈10 degrees) in the direction of an applied magnetic field over a large surface area at field strength as low as 2500 Gauss. Also, the Ni coating helped in protecting the copper core from oxidation resulting in better electrical wire-to-wire contacts. A nanowire-based interconnect channel was fabricated by combining magnetic field assisted alignment and deposition of aligned NWs on a thiol-modified and photolithography patterned CDO substrate. The NWs, deposited in the trenches, strongly bonded to the thiol-derivatized CDO substrate while an acetone wash removed loosely bound NWs on the photoresist surface. In electrical characterization, the directionally well-aligned Cu/Ni NWs channel displayed surprisingly two-fold higher conductivity than randomly arranged NWs channel. Close

• 9. [Article] A phytochemical investigation of liverwort Frullania franciscana Howe

  Liverwort Frullania franciscana Howe was found high on the allergic test scale by J. Mitchell of the Medical School of the University of British Columbia and co-workers. Frullanolide was isolated from ...

  Citation × Citation Citation Abstract Copy Title: A phytochemical investigation of liverwort Frullania franciscana Howe Author: Huang, Timothy Ta-E Year: 1974 Liverwort Frullania franciscana Howe was found high on the allergic test scale by J. Mitchell of the Medical School of the University of British Columbia and co-workers. Frullanolide was isolated from Frullania tamarisci by J.D. Connoly and by G. Oisson and his co-workers. The plant sample, collected in Oregon, was hand separated, confirmed, air dried and milled before the extractions were done. A Soxhlet extraction with ether and cold extractions with n-hexane and with ether were carried out. Ether is a better extraction solvent than n-hexane for cold extraction. Column chromatography was used for the separation of the extract based on gradient elution from silica gel or aluminum oxide. Non-polar hydro-carbon sesquiterpenes and other hydrocarbons usually were eluted first. Frullanolide then was eluted. Studies by thin layer chromatography on silica gel showed that none of the fractions was a pure component; therefore, further separations were done by thin layer chromatography and small-scale column chromatography. However, no satisfactory separation systems were found, except that frullanolide was isolated from the silica gel plate with cyclohexanel/ethyl acetate 80/20, Rf' = 25.8, which was very close to the reported value. An infrared spectrum of this was taken and used as supporting evidence. An infrared spectrum of the first fraction from an aluminum oxide column showed that this was a reasonably pure fraction of hydrocarbons. By gas chromatography, eleven components were found in this fraction, and the percentage of the major component was calculated to be 97% by weight. Nuclear magnetic resonance and infrared spectra showed an exo-double bond with a 6-membered ring or larger. (I.R. : 3080 cm-1 ,1643 cm-1 ,888 cm-1, NMR δ 4.73) This fraction was then studied by means of a gas chr0matography-mass spectrometer, and the molecular weight of the main component of this fraction was 204. Kovats’ indices of the main component were taken by co-injection with 0-cedrene and ᵝ-bourbonene; these data, however, did not match any of the compounds listed. Infrared analysis of the other fractions from the columns and from thin layer chromatography showed the presence of carbonyl groups. One of the carbonyl groups absorbed at about 1770 cm-1, characteristic of a y -lactone. Title: A phytochemical investigation of liverwort Frullania franciscana Howe Author: Huang, Timothy Ta-E Year: 1974 Liverwort Frullania franciscana Howe was found high on the allergic test scale by J. Mitchell of the Medical School of the University of British Columbia and co-workers. Frullanolide was isolated from Frullania tamarisci by J.D. Connoly and by G. Oisson and his co-workers. The plant sample, collected in Oregon, was hand separated, confirmed, air dried and milled before the extractions were done. A Soxhlet extraction with ether and cold extractions with n-hexane and with ether were carried out. Ether is a better extraction solvent than n-hexane for cold extraction. Column chromatography was used for the separation of the extract based on gradient elution from silica gel or aluminum oxide. Non-polar hydro-carbon sesquiterpenes and other hydrocarbons usually were eluted first. Frullanolide then was eluted. Studies by thin layer chromatography on silica gel showed that none of the fractions was a pure component; therefore, further separations were done by thin layer chromatography and small-scale column chromatography. However, no satisfactory separation systems were found, except that frullanolide was isolated from the silica gel plate with cyclohexanel/ethyl acetate 80/20, Rf' = 25.8, which was very close to the reported value. An infrared spectrum of this was taken and used as supporting evidence. An infrared spectrum of the first fraction from an aluminum oxide column showed that this was a reasonably pure fraction of hydrocarbons. By gas chromatography, eleven components were found in this fraction, and the percentage of the major component was calculated to be 97% by weight. Nuclear magnetic resonance and infrared spectra showed an exo-double bond with a 6-membered ring or larger. (I.R. : 3080 cm-1 ,1643 cm-1 ,888 cm-1, NMR δ 4.73) This fraction was then studied by means of a gas chr0matography-mass spectrometer, and the molecular weight of the main component of this fraction was 204. Kovats’ indices of the main component were taken by co-injection with 0-cedrene and ᵝ-bourbonene; these data, however, did not match any of the compounds listed. Infrared analysis of the other fractions from the columns and from thin layer chromatography showed the presence of carbonyl groups. One of the carbonyl groups absorbed at about 1770 cm-1, characteristic of a y -lactone. Close