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• 61. [Article] SIMPOL.1: a simple group contribution method for predicting vapor pressures and enthalpies of vaporization of multifunctional organic compounds

  The SIMPOL.1 group contribution method is developed for predicting the liquid vapor pressure poL (atm) and enthalpy of vaporization Δ Hvap (kJ mol-1) of organic compounds as functions of temperature (T). ...

  Citation × Citation Citation Abstract Copy Title: SIMPOL.1: a simple group contribution method for predicting vapor pressures and enthalpies of vaporization of multifunctional organic compounds Author: Pankow, James F., Asher, William E. Year: 2008 The SIMPOL.1 group contribution method is developed for predicting the liquid vapor pressure poL (atm) and enthalpy of vaporization Δ Hvap (kJ mol-1) of organic compounds as functions of temperature (T). For each compound i, the method assumes log10poL,i (T)=∑kνk,ibk(T) where νk,i is the number of groups of type k, and bk (T) is the contribution to log10poL,i (T) by each group of type k. A zeroeth group is included that uses b0 (T) with ν0,i=1 for all i. A total of 30 structural groups are considered: molecular carbon, alkyl hydroxyl, aromatic hydroxyl, alkyl ether, alkyl ring ether, aromatic ether, aldehyde, ketone, carboxylic acid, ester, nitrate, nitro, alkyl amine (primary, secondary, and tertiary), aromatic amine, amide (primary, secondary, and tertiary), peroxide, hydroperoxide, peroxy acid, C=C, carbonylperoxynitrate, nitro-phenol, nitro-ester, aromatic rings, non-aromatic rings, C=C–C=O in a non-aromatic ring, and carbon on the acid-side of an amide. The T dependence in each of the bk (T) is assumed to follow b(T)=B1/T+B2+B3T+B4ln T. Values of the B coefficients are fit using an initial basis set of 272 compounds for which experimentally based functions po L,i=fi (T) are available. The range of vapor pressure considered spans fourteen orders of magnitude. The ability of the initially fitted B coefficients to predict poL values is examined using a test set of 184 compounds and a T range that is as wide as 273.15 to 393.15 K for some compounds. σFIT is defined as the average over all points of the absolute value of the difference between experimental and predicted values of log10poL,i (T). After consideration of σFIT for the test set, the initial basis set and test set compounds are combined, and the B coefficients re-optimized. For all compounds and temperatures, σFIT=0.34: on average, poL,i (T) values are predicted to within a factor of 2. Because d(log10 poL,i (T))d(1/T) is related to the enthalpy of vaporization ΔHvap,i, the fitted B provide predictions of ΔHvap,i based on structure. Title: SIMPOL.1: a simple group contribution method for predicting vapor pressures and enthalpies of vaporization of multifunctional organic compounds Author: Pankow, James F., Asher, William E. Year: 2008 The SIMPOL.1 group contribution method is developed for predicting the liquid vapor pressure poL (atm) and enthalpy of vaporization Δ Hvap (kJ mol-1) of organic compounds as functions of temperature (T). For each compound i, the method assumes log10poL,i (T)=∑kνk,ibk(T) where νk,i is the number of groups of type k, and bk (T) is the contribution to log10poL,i (T) by each group of type k. A zeroeth group is included that uses b0 (T) with ν0,i=1 for all i. A total of 30 structural groups are considered: molecular carbon, alkyl hydroxyl, aromatic hydroxyl, alkyl ether, alkyl ring ether, aromatic ether, aldehyde, ketone, carboxylic acid, ester, nitrate, nitro, alkyl amine (primary, secondary, and tertiary), aromatic amine, amide (primary, secondary, and tertiary), peroxide, hydroperoxide, peroxy acid, C=C, carbonylperoxynitrate, nitro-phenol, nitro-ester, aromatic rings, non-aromatic rings, C=C–C=O in a non-aromatic ring, and carbon on the acid-side of an amide. The T dependence in each of the bk (T) is assumed to follow b(T)=B1/T+B2+B3T+B4ln T. Values of the B coefficients are fit using an initial basis set of 272 compounds for which experimentally based functions po L,i=fi (T) are available. The range of vapor pressure considered spans fourteen orders of magnitude. The ability of the initially fitted B coefficients to predict poL values is examined using a test set of 184 compounds and a T range that is as wide as 273.15 to 393.15 K for some compounds. σFIT is defined as the average over all points of the absolute value of the difference between experimental and predicted values of log10poL,i (T). After consideration of σFIT for the test set, the initial basis set and test set compounds are combined, and the B coefficients re-optimized. For all compounds and temperatures, σFIT=0.34: on average, poL,i (T) values are predicted to within a factor of 2. Because d(log10 poL,i (T))d(1/T) is related to the enthalpy of vaporization ΔHvap,i, the fitted B provide predictions of ΔHvap,i based on structure. Close

• 62. [Article] Environmental Swap Energy and Role of Configurational Entropy in Transfer of Small Molecules from Water into Alkanes

  We studied the effect of segmented solvent molecules on the free energy of transfer of small molecules from water into alkanes (hexane, heptane, octane, decane, dodecane, tetradecane, and hexadecane). ...

  Citation × Citation Citation Abstract Copy Title: Environmental Swap Energy and Role of Configurational Entropy in Transfer of Small Molecules from Water into Alkanes Author: Smejtek, Pavel, Word, Robert Campbell Year: 2004 We studied the effect of segmented solvent molecules on the free energy of transfer of small molecules from water into alkanes (hexane, heptane, octane, decane, dodecane, tetradecane, and hexadecane). For these alkanes we measured partition coefficients of benzene, 3-methylindole (3MI), 2,3,4,6-tetrachlorophenol (TeCP), and 2,4,6-tribromophenol (TriBP) at 3, 11, 20, 3, and 47 °C. For 3MI, TeCP, and TriBP the dependence of free energy of transfer on length of alkane chains was found to be very different from that for benzene. In contrast to benzene, the energy of transfer for 3MI, TeCP, and TriBP was independent of the number of carbons in alkanes. To interpret data, we used the classic Flory–Huggins (FH) theory of concentrated polymer solutions for the alkane phase. For benzene, the measured dependence of energy of transfer on the number of carbons in alkanes agreed well with predictions based on FH model in which the size of alkane segments was obtained from the ratio of molar volumes of alkanes and the solute. We show that for benzene, the energy of transfer can be divided into two components, one called environmental swap energy (ESE), and one representing the contribution of configurational entropy of alkane chains. For 3MI, TeCP, and TriBP the contribution of configurational entropy was not measurable even though the magnitude of the effect predicted from the FH model for short chain alkanes was as much as 20 times greater than experimental uncertainties. From the temperature dependence of ESE we obtained enthalpy and entropy of transfer for benzene, 3MI, TeCP, and TriBP. Experimental results are discussed in terms of a thermodynamic cycle considering creation of cavity, insertion of solute, and activation of solute-medium attractive interactions. Our results suggest that correcting experimental free energy of transfer by Flory–Huggins configurational entropy term is not generally appropriate and cannot be applied indiscriminately. An Erratum has been published and is located here: http://archives.pdx.edu/ds/psu/8365 Title: Environmental Swap Energy and Role of Configurational Entropy in Transfer of Small Molecules from Water into Alkanes Author: Smejtek, Pavel, Word, Robert Campbell Year: 2004 We studied the effect of segmented solvent molecules on the free energy of transfer of small molecules from water into alkanes (hexane, heptane, octane, decane, dodecane, tetradecane, and hexadecane). For these alkanes we measured partition coefficients of benzene, 3-methylindole (3MI), 2,3,4,6-tetrachlorophenol (TeCP), and 2,4,6-tribromophenol (TriBP) at 3, 11, 20, 3, and 47 °C. For 3MI, TeCP, and TriBP the dependence of free energy of transfer on length of alkane chains was found to be very different from that for benzene. In contrast to benzene, the energy of transfer for 3MI, TeCP, and TriBP was independent of the number of carbons in alkanes. To interpret data, we used the classic Flory–Huggins (FH) theory of concentrated polymer solutions for the alkane phase. For benzene, the measured dependence of energy of transfer on the number of carbons in alkanes agreed well with predictions based on FH model in which the size of alkane segments was obtained from the ratio of molar volumes of alkanes and the solute. We show that for benzene, the energy of transfer can be divided into two components, one called environmental swap energy (ESE), and one representing the contribution of configurational entropy of alkane chains. For 3MI, TeCP, and TriBP the contribution of configurational entropy was not measurable even though the magnitude of the effect predicted from the FH model for short chain alkanes was as much as 20 times greater than experimental uncertainties. From the temperature dependence of ESE we obtained enthalpy and entropy of transfer for benzene, 3MI, TeCP, and TriBP. Experimental results are discussed in terms of a thermodynamic cycle considering creation of cavity, insertion of solute, and activation of solute-medium attractive interactions. Our results suggest that correcting experimental free energy of transfer by Flory–Huggins configurational entropy term is not generally appropriate and cannot be applied indiscriminately. An Erratum has been published and is located here: http://archives.pdx.edu/ds/psu/8365 Close

• 63. [Article] Indirect-Drive Noncryogenic Double-Shell Ignition Targets for the National Ignition Facility: Design and Analysis

  Analysis and design of indirect-drive National Ignition Facility double-shell targets with hohlraum temperatures of 200 eV and 250 eV are presented. The analysis of these targets includes the assessment ...

  Citation × Citation Citation Abstract Copy Title: Indirect-Drive Noncryogenic Double-Shell Ignition Targets for the National Ignition Facility: Design and Analysis Author: Amendt, Peter A., Colvin, J. D., Tipton, R. E., Hinkel, D. E., Edwards, M. J., Landen, O. L., Ramshaw, John D., Suter, L. J., Varnum, W. S., Watt, R. G. Year: 2002 Analysis and design of indirect-drive National Ignition Facility double-shell targets with hohlraum temperatures of 200 eV and 250 eV are presented. The analysis of these targets includes the assessment of two-dimensional radiation asymmetry and nonlinear mix. Two-dimensional integrated hohlraum simulations indicate that the x-ray illumination can be adjusted to provide adequate symmetry control in hohlraums specially designed to have high laser-coupling efficiency [Suter et al., Phys. Plasmas 7, 2092 (2000)]. These simulations also reveal the need to diagnose and control localized 10?15 keV x-ray emission from the high-Z hohlraum wall because of strong absorption by the high-Z inner shell. Preliminary estimates of the degree of laser backscatter from an assortment of laser?plasma interactions suggest comparatively benign hohlraum conditions. The application of a variety of nonlinear mix models and phenomenological tools, including buoyancy-drag models, multimode simulations and fall-line optimization, indicates a possibility of achieving ignition, i.e., fusion yields greater than 1 MJ. Planned experiments on the Omega laser will test current understanding of high-energy radiation flux asymmetry and mix-induced yield degradation in double-shell targets. Title: Indirect-Drive Noncryogenic Double-Shell Ignition Targets for the National Ignition Facility: Design and Analysis Author: Amendt, Peter A., Colvin, J. D., Tipton, R. E., Hinkel, D. E., Edwards, M. J., Landen, O. L., Ramshaw, John D., Suter, L. J., Varnum, W. S., Watt, R. G. Year: 2002 Analysis and design of indirect-drive National Ignition Facility double-shell targets with hohlraum temperatures of 200 eV and 250 eV are presented. The analysis of these targets includes the assessment of two-dimensional radiation asymmetry and nonlinear mix. Two-dimensional integrated hohlraum simulations indicate that the x-ray illumination can be adjusted to provide adequate symmetry control in hohlraums specially designed to have high laser-coupling efficiency [Suter et al., Phys. Plasmas 7, 2092 (2000)]. These simulations also reveal the need to diagnose and control localized 10?15 keV x-ray emission from the high-Z hohlraum wall because of strong absorption by the high-Z inner shell. Preliminary estimates of the degree of laser backscatter from an assortment of laser?plasma interactions suggest comparatively benign hohlraum conditions. The application of a variety of nonlinear mix models and phenomenological tools, including buoyancy-drag models, multimode simulations and fall-line optimization, indicates a possibility of achieving ignition, i.e., fusion yields greater than 1 MJ. Planned experiments on the Omega laser will test current understanding of high-energy radiation flux asymmetry and mix-induced yield degradation in double-shell targets. Close

• 64. [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

• 65. [Article] Improved Gain Stability of a Digital Imager Using a Charge Feedback Amplifier

  Digital imagers including Charge-Coupled Devices (CCD) are essential to most forms of modern photographic technologies. The quality of the data produced by digital imagers have made them an invaluable ...

  Citation × Citation Citation Abstract Copy Title: Improved Gain Stability of a Digital Imager Using a Charge Feedback Amplifier Author: Mylott, Elliot Eckman Year: 2015 Digital imagers including Charge-Coupled Devices (CCD) are essential to most forms of modern photographic technologies. The quality of the data produced by digital imagers have made them an invaluable scientific measurement tool. Despite the numerous advantages of digital imagers, there are still factors that limit their performance. One such factor is the stability of the camera's gain, the ratio that dictates the imager's ability to convert incident photons to a measurable output voltage. Variations in gain can affect the linearity of the device and produce inaccurate measurements. One of the factors that determines the gain of the camera is the sensitivity of the output amplifier. The purpose of this study is to compare the performance of two different output amplifier structures: the traditional source follower (SF) and the charge feedback amplifier (CFA). In studies of other solid state detectors, the CFA has shown a greater stability against variations in certain system parameters and environmental conditions such as operating temperature. It is thought that the CFA shows a superior stability over the SF, because the gain of the SF is dependent on multiple capacitances associated with the reset and output transistors, whereas the CFA gain is only dependent on its feedback capacitance. Furthermore, the CFA is able to handle a larger amount of charge than the SF, which increases the dynamic range of the output amplifier. In this research, output amplifier stability is measured using gain and linearity data collected from a CCD manufactured with both types of amplifiers. Preliminary data is presented that indicates the CFA exhibits a greater linearity, larger dynamic range, and a more stable gain than the SF. Despite this the CFA suffers from a significantly larger level of noise. Suggestions for future research are also given as to how to verify and expand upon the results presented here. Title: Improved Gain Stability of a Digital Imager Using a Charge Feedback Amplifier Author: Mylott, Elliot Eckman Year: 2015 Digital imagers including Charge-Coupled Devices (CCD) are essential to most forms of modern photographic technologies. The quality of the data produced by digital imagers have made them an invaluable scientific measurement tool. Despite the numerous advantages of digital imagers, there are still factors that limit their performance. One such factor is the stability of the camera's gain, the ratio that dictates the imager's ability to convert incident photons to a measurable output voltage. Variations in gain can affect the linearity of the device and produce inaccurate measurements. One of the factors that determines the gain of the camera is the sensitivity of the output amplifier. The purpose of this study is to compare the performance of two different output amplifier structures: the traditional source follower (SF) and the charge feedback amplifier (CFA). In studies of other solid state detectors, the CFA has shown a greater stability against variations in certain system parameters and environmental conditions such as operating temperature. It is thought that the CFA shows a superior stability over the SF, because the gain of the SF is dependent on multiple capacitances associated with the reset and output transistors, whereas the CFA gain is only dependent on its feedback capacitance. Furthermore, the CFA is able to handle a larger amount of charge than the SF, which increases the dynamic range of the output amplifier. In this research, output amplifier stability is measured using gain and linearity data collected from a CCD manufactured with both types of amplifiers. Preliminary data is presented that indicates the CFA exhibits a greater linearity, larger dynamic range, and a more stable gain than the SF. Despite this the CFA suffers from a significantly larger level of noise. Suggestions for future research are also given as to how to verify and expand upon the results presented here. Close

• 66. [Article] Doubled CO2 Experiments With the Global Change Research Center Two-Dimensional Statistical Dynamical Climate Model

  The zonally averaged response of the Global Change Research Center two-dimensional statistical dynamical climate model (GCRC 2-D SDCM) to a doubling of atmospheric carbon dioxide (350 parts per million ...

  Citation × Citation Citation Abstract Copy Title: Doubled CO2 Experiments With the Global Change Research Center Two-Dimensional Statistical Dynamical Climate Model Author: MacKay, R. M., Khalil, M. A. K. Year: 1995 The zonally averaged response of the Global Change Research Center two-dimensional statistical dynamical climate model (GCRC 2-D SDCM) to a doubling of atmospheric carbon dioxide (350 parts per million by volume (ppmv) to 700 ppmv) is reported. The model solves the two-dimensional primitive equations in finite difference form (mass continuity, Newton's second law, and the first law of thermodynamics) for the prognostic variables: zonal mean density, zonal mean zonal velocity, zonal mean meridional velocity, and zonal mean temperature on a grid that has 18 nodes in latitude and 9 vertical nodes (plus the surface). The equation of state, p=rhoRT, and an assumed hydrostatic atmosphere, Deltap=rhogDeltaz, are used to diagnostically calculate the zonal mean pressure and vertical velocity for each grid node, and the moisture balance equation is used to estimate the precipitation rate. The model includes seasonal variations in solar intensity, including the effects of eccentricity, and has observed land and ocean fractions set for each zone. Seasonally varying values of cloud amounts, relative humidity profiles, ozone, and sea ice are all prescribed in the model. Equator to pole ocean heat transport is simulated in the model by turbulent diffusion. Title: Doubled CO2 Experiments With the Global Change Research Center Two-Dimensional Statistical Dynamical Climate Model Author: MacKay, R. M., Khalil, M. A. K. Year: 1995 The zonally averaged response of the Global Change Research Center two-dimensional statistical dynamical climate model (GCRC 2-D SDCM) to a doubling of atmospheric carbon dioxide (350 parts per million by volume (ppmv) to 700 ppmv) is reported. The model solves the two-dimensional primitive equations in finite difference form (mass continuity, Newton's second law, and the first law of thermodynamics) for the prognostic variables: zonal mean density, zonal mean zonal velocity, zonal mean meridional velocity, and zonal mean temperature on a grid that has 18 nodes in latitude and 9 vertical nodes (plus the surface). The equation of state, p=rhoRT, and an assumed hydrostatic atmosphere, Deltap=rhogDeltaz, are used to diagnostically calculate the zonal mean pressure and vertical velocity for each grid node, and the moisture balance equation is used to estimate the precipitation rate. The model includes seasonal variations in solar intensity, including the effects of eccentricity, and has observed land and ocean fractions set for each zone. Seasonally varying values of cloud amounts, relative humidity profiles, ozone, and sea ice are all prescribed in the model. Equator to pole ocean heat transport is simulated in the model by turbulent diffusion. Close

• 67. [Article] Field programmable gate array based reconfigurable scanning probe/optical microscope

  The increasing popularity of nanometrology and nanospectroscopy has pushed researchers to develop complex new analytical systems. This paper describes the development of a platform on which to build a ...

  Citation × Citation Citation Abstract Copy Title: Field programmable gate array based reconfigurable scanning probe/optical microscope Author: Nowak, Derek Brant, Lawrence, Andrew James, Dzegede, Zechariah K., Hiester, Justin C., Kim, Cliff, Sánchez, Erik J. Year: 2011 The increasing popularity of nanometrology and nanospectroscopy has pushed researchers to develop complex new analytical systems. This paper describes the development of a platform on which to build a microscopy tool that will allow for flexibility of customization to suit research needs. The novelty of the described system lies in its versatility of capabilities. So far, one version of this microscope has allowed for successful near-field and far-field fluorescence imaging with single molecule detection sensitivity. This system is easily adapted for reflection, polarization (Kerr magneto-optical (MO)), Raman, super-resolution techniques, and other novel scanning probe imaging and spectroscopic designs. While collecting a variety of forms of optical images, the system can simultaneously monitor topographic information of a sample with an integrated tuning fork based shear force system. The instrument has the ability to image at room temperature and atmospheric pressure or under liquid. The core of the design is a field programmable gate array (FPGA) data acquisition card and a single, low cost computer to control the microscope with analog control circuitry using off-the-shelf available components. A detailed description of electronics, mechanical requirements, and software algorithms as well as examples of some different forms of the microscope developed so far are discussed. Title: Field programmable gate array based reconfigurable scanning probe/optical microscope Author: Nowak, Derek Brant, Lawrence, Andrew James, Dzegede, Zechariah K., Hiester, Justin C., Kim, Cliff, Sánchez, Erik J. Year: 2011 The increasing popularity of nanometrology and nanospectroscopy has pushed researchers to develop complex new analytical systems. This paper describes the development of a platform on which to build a microscopy tool that will allow for flexibility of customization to suit research needs. The novelty of the described system lies in its versatility of capabilities. So far, one version of this microscope has allowed for successful near-field and far-field fluorescence imaging with single molecule detection sensitivity. This system is easily adapted for reflection, polarization (Kerr magneto-optical (MO)), Raman, super-resolution techniques, and other novel scanning probe imaging and spectroscopic designs. While collecting a variety of forms of optical images, the system can simultaneously monitor topographic information of a sample with an integrated tuning fork based shear force system. The instrument has the ability to image at room temperature and atmospheric pressure or under liquid. The core of the design is a field programmable gate array (FPGA) data acquisition card and a single, low cost computer to control the microscope with analog control circuitry using off-the-shelf available components. A detailed description of electronics, mechanical requirements, and software algorithms as well as examples of some different forms of the microscope developed so far are discussed. Close

• 68. [Article] Numerical Simulation of Nonequilibrium Effects in an Argon Plasma Jet

  Departures from thermal (translational), ionization, and excitation equilibrium in an axisymmetric argon plasma jet have been studied by two?dimensional numerical simulations. Electrons, ions, and excited ...

  Citation × Citation Citation Abstract Copy Title: Numerical Simulation of Nonequilibrium Effects in an Argon Plasma Jet Author: Chang, C. H., Ramshaw, John D. Year: 1994 Departures from thermal (translational), ionization, and excitation equilibrium in an axisymmetric argon plasma jet have been studied by two?dimensional numerical simulations. Electrons, ions, and excited and ground states of neutral atoms are represented as separate chemical species in the mixture. Transitions between excited states, as well as ionization/recombination reactions due to both collisional and radiative processes, are treated as separate chemical reactions. Resonance radiation transport is represented using Holstein escape factors to simulate both the optically thin and optically thick limits. The optically thin calculation showed significant underpopulation of excited species in the upstream part of the jet core, whereas in the optically thick calculation this region remains close to local thermodynamic equilibrium, consistent with previous experimental observations. Resonance radiation absorption is therefore an important effect. The optically thick calculation results also show overpopulations (relative to equilibrium) of excited species and electron densities in the fringes and downstream part of the jet core. In these regions, however, the electrons and ions are essentially in partial local thermodynamic equilibrium with the excited state at the electron temperature, even though the ionized and excited states are no longer in equilibrium with the ground state. Departures from partial local thermodynamic equilibrium are observed in the outer fringes and far downstream part of the jet. These results are interpreted in terms of the local relative time scales for the various physical and chemical processes occurring in the plasma. Title: Numerical Simulation of Nonequilibrium Effects in an Argon Plasma Jet Author: Chang, C. H., Ramshaw, John D. Year: 1994 Departures from thermal (translational), ionization, and excitation equilibrium in an axisymmetric argon plasma jet have been studied by two?dimensional numerical simulations. Electrons, ions, and excited and ground states of neutral atoms are represented as separate chemical species in the mixture. Transitions between excited states, as well as ionization/recombination reactions due to both collisional and radiative processes, are treated as separate chemical reactions. Resonance radiation transport is represented using Holstein escape factors to simulate both the optically thin and optically thick limits. The optically thin calculation showed significant underpopulation of excited species in the upstream part of the jet core, whereas in the optically thick calculation this region remains close to local thermodynamic equilibrium, consistent with previous experimental observations. Resonance radiation absorption is therefore an important effect. The optically thick calculation results also show overpopulations (relative to equilibrium) of excited species and electron densities in the fringes and downstream part of the jet core. In these regions, however, the electrons and ions are essentially in partial local thermodynamic equilibrium with the excited state at the electron temperature, even though the ionized and excited states are no longer in equilibrium with the ground state. Departures from partial local thermodynamic equilibrium are observed in the outer fringes and far downstream part of the jet. These results are interpreted in terms of the local relative time scales for the various physical and chemical processes occurring in the plasma. Close

• 69. [Article] Thin Film Solar Cells Using ZnO Nanowires, Organic Semiconductors and Quantum Dots

  A thin film organic/ inorganic hybrid solar cell was fabricated by incorporating ZnO nanowires, n- and p-type organic semiconductors and inorganic quantum dots. The basic cell design involved the electrodeposition ...

  Citation × Citation Citation Abstract Copy Title: Thin Film Solar Cells Using ZnO Nanowires, Organic Semiconductors and Quantum Dots Author: VanSant, Kaitlyn Year: 2007 A thin film organic/ inorganic hybrid solar cell was fabricated by incorporating ZnO nanowires, n- and p-type organic semiconductors and inorganic quantum dots. The basic cell design involved the electrodeposition of ZnO nanowires grown on a substrate coated with a transparent conductive oxide. The ZnO nanowires were coated with a thin layer of an organic n-type material, followed by a deposition of inorganic quantum dots. A p-type polymer layer was subsequently deposited and the sample was then contacted with gold to form a quantum dot layer sandwiched between a p-n junction of organic conductive materials. Various materials and processing methods were adjusted, using I-V characteristics, photovoltage and/ or photocurrent measurements to determine the performance of the cell. Each constituent material in the basic device design was evaluated in terms of its contribution to the sample characteristics. A variety of deposition techniques were investigated to obtain homogeneous layers. Different annealing procedures were explored with the intent of balancing the time and temperatures required for electrical activation with material constraints such as tendency towards oxidation and low melting points. The effect of time on the sample characteristics was also observed. The evaluation primarily includes data for samples that led to design modifications aimed at improving both electrical properties and quantum efficiencies. This research led to the development of a hybrid solar cell sensitized by the addition of quantum dots. The organic semiconductors were used to form a p-n junction, and the p-type polymer also served as an active absorber layer. The quantum dots were used as the inorganic absorber fayer, and the results show that the range of optical absorption in the cell can be modified by adjusting particle size. In addition, the ZnO nanowires appear to improve charge transfer, when used with materials that have favorable band offsets. Title: Thin Film Solar Cells Using ZnO Nanowires, Organic Semiconductors and Quantum Dots Author: VanSant, Kaitlyn Year: 2007 A thin film organic/ inorganic hybrid solar cell was fabricated by incorporating ZnO nanowires, n- and p-type organic semiconductors and inorganic quantum dots. The basic cell design involved the electrodeposition of ZnO nanowires grown on a substrate coated with a transparent conductive oxide. The ZnO nanowires were coated with a thin layer of an organic n-type material, followed by a deposition of inorganic quantum dots. A p-type polymer layer was subsequently deposited and the sample was then contacted with gold to form a quantum dot layer sandwiched between a p-n junction of organic conductive materials. Various materials and processing methods were adjusted, using I-V characteristics, photovoltage and/ or photocurrent measurements to determine the performance of the cell. Each constituent material in the basic device design was evaluated in terms of its contribution to the sample characteristics. A variety of deposition techniques were investigated to obtain homogeneous layers. Different annealing procedures were explored with the intent of balancing the time and temperatures required for electrical activation with material constraints such as tendency towards oxidation and low melting points. The effect of time on the sample characteristics was also observed. The evaluation primarily includes data for samples that led to design modifications aimed at improving both electrical properties and quantum efficiencies. This research led to the development of a hybrid solar cell sensitized by the addition of quantum dots. The organic semiconductors were used to form a p-n junction, and the p-type polymer also served as an active absorber layer. The quantum dots were used as the inorganic absorber fayer, and the results show that the range of optical absorption in the cell can be modified by adjusting particle size. In addition, the ZnO nanowires appear to improve charge transfer, when used with materials that have favorable band offsets. Close

• 70. [Article] An Analysis of the Optimal Mix of Global Energy Resources and the Potential Need for Geoengineering Using the CEAGOM Model

  Humanity faces tremendous challenges as a result of anthropogenic climate change caused by greenhouse gas emissions. The mix of resources deployed in order to meet the energy needs of a growing global ...

  Citation × Citation Citation Abstract Copy Title: An Analysis of the Optimal Mix of Global Energy Resources and the Potential Need for Geoengineering Using the CEAGOM Model Author: Anasis, John George, Khalil, M. A. K., Lendaris, George G., Butenhoff, Christopher L., Bluffstone, Randall Year: 2017 Humanity faces tremendous challenges as a result of anthropogenic climate change caused by greenhouse gas emissions. The mix of resources deployed in order to meet the energy needs of a growing global population is key to addressing the climate change issue. The goal of this research is to examine the optimal mix of energy resources that should be deployed to meet a forecast global energy demand while still meeting desired climate targets. The research includes the unique feature of examining the role that geoengineering can play in this optimization. The results show that some form of geoengineering is likely to be needed by the middle of the 21st century as part of the optimal energy strategy in order to meet a specified climate goal of 580 ppm CO2-eq greenhouse gas concentration (or ≈2 °C average global temperature rise). The optimal energy mix would need to rely on energy efficiency, nuclear, geothermal, hydro, and wind energy for over 50% of global energy needs. In addition, the overall cost of the optimal energy mix is sensitive to the assumed amount of achievable energy efficiency, carbon taxes, deployment of electric vehicles, and the assumed discount rate. Title: An Analysis of the Optimal Mix of Global Energy Resources and the Potential Need for Geoengineering Using the CEAGOM Model Author: Anasis, John George, Khalil, M. A. K., Lendaris, George G., Butenhoff, Christopher L., Bluffstone, Randall Year: 2017 Humanity faces tremendous challenges as a result of anthropogenic climate change caused by greenhouse gas emissions. The mix of resources deployed in order to meet the energy needs of a growing global population is key to addressing the climate change issue. The goal of this research is to examine the optimal mix of energy resources that should be deployed to meet a forecast global energy demand while still meeting desired climate targets. The research includes the unique feature of examining the role that geoengineering can play in this optimization. The results show that some form of geoengineering is likely to be needed by the middle of the 21st century as part of the optimal energy strategy in order to meet a specified climate goal of 580 ppm CO2-eq greenhouse gas concentration (or ≈2 °C average global temperature rise). The optimal energy mix would need to rely on energy efficiency, nuclear, geothermal, hydro, and wind energy for over 50% of global energy needs. In addition, the overall cost of the optimal energy mix is sensitive to the assumed amount of achievable energy efficiency, carbon taxes, deployment of electric vehicles, and the assumed discount rate. Close