1) The document describes the development of an ion source for a compact 14C AMS spectrometer dedicated to biomedical applications.
2) The ion source directly accepts CO2 samples for analysis and features a 50-sample carousel, easy maintenance, and low memory effects for optimal performance in biomedical research.
3) Initial testing of the ion source showed analyzed 12C currents of 50-100 μA from graphite samples and 5-10 μA from CO2 samples, demonstrating its ability to handle both sample types for 14C AMS analysis.
Presentation given by Professor Colin Snape from University of Nottingham on "Performance Enhanced Activated Spherical Carbon Adsorbents for CO2 Capture" in the Capture Technical Session on Solid Adsorption at the UKCCSRC Biannual Meeting - CCS in the Bigger Picture - held in Cambridge on 2-3 April 2014
This document summarizes research conducted at ISIS on energy materials. It discusses how neutron and x-ray techniques are used across multiple length scales to study materials related to energy production, storage and efficiency. Specific examples are given on the study of hydrogen storage alloys, carbon dioxide sequestration materials, and lithium ion battery electrode materials. The research aims to develop new environmentally friendly energy technologies through improved fundamental understanding of materials properties and structures.
This document summarizes a study on coating activated carbon from oil palm shells with magnetite particles for use in adsorbing Cu(II) ions from solutions. The activated carbon was synthesized from oil palm shells and coated with magnetite. Batch adsorption experiments explored the effects of adsorbent dosage, contact time, and ion concentration on Cu(II) ion removal. Kinetic data fit a pseudo-second order model and isotherm data fit the Langmuir model best, indicating chemisorption. The magnetite-coated activated carbon showed potential for removing heavy metals from water.
1. The document investigates the electrodeposition of FeCoNiCu/Cu and CrFeCoNiCu/Cu multilayered nanowires for applications in magnetic sensing devices. It explores fabrication methods to achieve better sensitivity, low coercivity, and low magnetic saturation.
2. Experiments are conducted to characterize electrolyte compositions and deposition parameters. Constant potential and pulsed potential techniques are used to fabricate multilayers. Composition and magnetic properties are analyzed. Maximum giant magnetoresistance of 10.64% is achieved for optimized layer thickness and saturation field.
3. Adding chromium is expected to further improve properties like reducing coercivity based on prior research on chromium's effects in other material systems.
This document summarizes a study comparing the effects of two different etching solutions, HCl-based and H3PO4-based, on the surface chemistry and electrical performance of InAs/GaSb type-II superlattice materials. X-ray photoelectron spectroscopy (XPS) characterization revealed that the HCl-based etch removed Ga and Sb oxides, while the H3PO4-based etch removed In and As oxides. Electrical testing of photodiodes fabricated with each etching treatment showed over an order of magnitude lower dark current for devices treated with the H3PO4 solution. This suggests the H3PO4 treatment is more effective at passivation and reducing surface leakage currents.
Power and Dipple MgO carbon sequestrationPeter Francis
This study assessed the carbon sequestration potential of magnesium oxychloride cement boards by 1) documenting the fate of fixed CO2 within the boards, 2) fingerprinting the source of CO2 to confirm its value as a greenhouse gas offset, 3) determining the passive rate of CO2 sequestration under ambient factory conditions, and 4) determining the potential to accelerate sequestration using elevated CO2 concentrations. The results showed plates of magnesium carbonate forming within the boards, stable carbon and oxygen isotope analysis confirming atmospheric CO2 sequestration, an estimated passive sequestration rate of 1 kg CO2/m2 over 15 years, and storage under 100% CO2 accelerating the rate by
The effect of copper conversion plates on low-Z target image qualityDavid Parsons
1) The presence of copper in an electronic portal imaging device (EPID) decreases the proportion of low-energy diagnostic photons reaching the detector and suppresses detector response at low energies.
2) Removing the copper conversion plate from the EPID can increase planar contrast-to-noise ratio (CNR) by a factor of 1.4-4.0 and cone beam computed tomography (CBCT) CNR by 1.3-2.1 when imaging with a low atomic number target beam.
3) The results suggest removing the copper conversion plate from the EPID to improve image quality for planar and CBCT imaging with low atomic number target beams.
Presentation given by Professor Colin Snape from University of Nottingham on "Performance Enhanced Activated Spherical Carbon Adsorbents for CO2 Capture" in the Capture Technical Session on Solid Adsorption at the UKCCSRC Biannual Meeting - CCS in the Bigger Picture - held in Cambridge on 2-3 April 2014
This document summarizes research conducted at ISIS on energy materials. It discusses how neutron and x-ray techniques are used across multiple length scales to study materials related to energy production, storage and efficiency. Specific examples are given on the study of hydrogen storage alloys, carbon dioxide sequestration materials, and lithium ion battery electrode materials. The research aims to develop new environmentally friendly energy technologies through improved fundamental understanding of materials properties and structures.
This document summarizes a study on coating activated carbon from oil palm shells with magnetite particles for use in adsorbing Cu(II) ions from solutions. The activated carbon was synthesized from oil palm shells and coated with magnetite. Batch adsorption experiments explored the effects of adsorbent dosage, contact time, and ion concentration on Cu(II) ion removal. Kinetic data fit a pseudo-second order model and isotherm data fit the Langmuir model best, indicating chemisorption. The magnetite-coated activated carbon showed potential for removing heavy metals from water.
1. The document investigates the electrodeposition of FeCoNiCu/Cu and CrFeCoNiCu/Cu multilayered nanowires for applications in magnetic sensing devices. It explores fabrication methods to achieve better sensitivity, low coercivity, and low magnetic saturation.
2. Experiments are conducted to characterize electrolyte compositions and deposition parameters. Constant potential and pulsed potential techniques are used to fabricate multilayers. Composition and magnetic properties are analyzed. Maximum giant magnetoresistance of 10.64% is achieved for optimized layer thickness and saturation field.
3. Adding chromium is expected to further improve properties like reducing coercivity based on prior research on chromium's effects in other material systems.
This document summarizes a study comparing the effects of two different etching solutions, HCl-based and H3PO4-based, on the surface chemistry and electrical performance of InAs/GaSb type-II superlattice materials. X-ray photoelectron spectroscopy (XPS) characterization revealed that the HCl-based etch removed Ga and Sb oxides, while the H3PO4-based etch removed In and As oxides. Electrical testing of photodiodes fabricated with each etching treatment showed over an order of magnitude lower dark current for devices treated with the H3PO4 solution. This suggests the H3PO4 treatment is more effective at passivation and reducing surface leakage currents.
Power and Dipple MgO carbon sequestrationPeter Francis
This study assessed the carbon sequestration potential of magnesium oxychloride cement boards by 1) documenting the fate of fixed CO2 within the boards, 2) fingerprinting the source of CO2 to confirm its value as a greenhouse gas offset, 3) determining the passive rate of CO2 sequestration under ambient factory conditions, and 4) determining the potential to accelerate sequestration using elevated CO2 concentrations. The results showed plates of magnesium carbonate forming within the boards, stable carbon and oxygen isotope analysis confirming atmospheric CO2 sequestration, an estimated passive sequestration rate of 1 kg CO2/m2 over 15 years, and storage under 100% CO2 accelerating the rate by
The effect of copper conversion plates on low-Z target image qualityDavid Parsons
1) The presence of copper in an electronic portal imaging device (EPID) decreases the proportion of low-energy diagnostic photons reaching the detector and suppresses detector response at low energies.
2) Removing the copper conversion plate from the EPID can increase planar contrast-to-noise ratio (CNR) by a factor of 1.4-4.0 and cone beam computed tomography (CBCT) CNR by 1.3-2.1 when imaging with a low atomic number target beam.
3) The results suggest removing the copper conversion plate from the EPID to improve image quality for planar and CBCT imaging with low atomic number target beams.
This document describes research into using pulsed anodic arc discharges to synthesize carbon nanomaterials. Pulsed arcs with frequencies of 1-5 Hz and a 10% duty cycle were generated between graphite electrodes in a helium atmosphere. Plasma parameters like electron density (1016-1017 m-3) and temperature (0.5-2.0 eV) were measured. Carbon nanostructures like graphene nanoplatelets and carbon nanotubes were deposited on the cathode. Pulsed arcs showed higher peak currents than steady DC arcs but did not reach steady state levels. This pulsed method could improve control over carbon nanomaterial synthesis compared to conventional DC arcs.
Paper spray ionization was paired with a mechanical-gate ion mobility spectrometer to detect herbicide ions. The ion mobility spectrometer contained a drift tube with stainless steel rings and resistors, a detector, and a mechanical gate. Paper spray ionization used high voltage applied to filter paper wetted with analyte solution to create ions. Blank samples consistently produced two peaks likely from protonated water and methanol clusters. Samples with the herbicide prometon consistently showed three peaks, including one from protonated prometon clusters. Aperture grids were investigated to reduce peak width but lowered signal. Future work will optimize peak resolution and identification.
This document describes a method for synthesizing nitrogen-doped porous graphitic carbon materials for use as electrodes in supercapacitors. The method involves polymerizing aniline in the presence of ferric chloride, followed by high-temperature treatment and chemical activation to produce a 3D porous structure. The novel carbon material demonstrated a high specific capacitance of 300 F/g as an electrode in aqueous electrolyte. Further characterization showed the material had a surface area of over 1200 m2/g after activation.
Importance of plasma conditions for vertically aligned carbon nanowalls synth...Marcel Mesko
This document discusses the importance of plasma conditions for vertically aligned carbon nanowall synthesis. It summarizes the plasma concepts and fundamentals relevant for nanofabrication. It also examines the effects of bombarding ions and electric fields on the alignment mechanisms of carbon nanotubes and nanowalls during plasma-assisted growth. Furthermore, it explores the use of direct and remote plasma processes to reduce graphite oxide materials.
The document summarizes a hyphenated technique combining capillary electrophoresis (CE) and inductively coupled plasma mass spectrometry (ICP-MS) for elemental speciation analysis. It discusses the CE-ICP-MS instrumentation including interface designs, applications to analyze arsenic and chromium species in preserved wood and soil, and preliminary results examining interface configurations and gas flow rates.
1) The SPARC-EBIT is a new electron beam ion trap (EBIT) installed at GSI for testing as an injector for HITRAP and as a charge breeder.
2) Current experiments are characterizing the SPARC-EBIT and testing its capabilities for ion production, x-ray spectroscopy, and charge breeding.
3) Future plans include using the SPARC-EBIT as an offline injector for HITRAP and developing it as a charge breeder for the MATS facility.
This study evaluated using an electrocoagulation process with solar power to remove excess phosphorus from surface waters. The process uses aluminum electrodes and an applied electric current to dissolve the metal into the water, facilitating the removal of phosphates through precipitation and coagulation. Testing of the laboratory scale reactor showed it was capable of removing 99% of phosphates from synthetic water, surface water, and treated wastewater. The removal efficiency increased with higher conductivity and more applied power. Testing also demonstrated the system could reduce total and fecal coliform bacteria by 90-99% with increased voltage.
The document summarizes research on synthesizing graphene via chemical vapor deposition for use in supercapacitor electrodes. It describes using CVD to deposit graphene on copper foil substrates by flowing methane and hydrogen gases into a heated furnace. Experiments varied the hydrogen flow rate and growth time, finding that higher hydrogen levels and shorter times produced higher quality mono-layer graphene, as shown through Raman spectroscopy analysis. The document also explores electropolishing copper substrates and transferring graphene to other substrates for use in supercapacitors.
International Journal of Research in Engineering and Science is an open access peer-reviewed international forum for scientists involved in research to publish quality and refereed papers. Papers reporting original research or experimentally proved review work are welcome. Papers for publication are selected through peer review to ensure originality, relevance, and readability.
The process of photo thermal evaporation in nanofluids finds promising applications in solar energetics, medicine and process technology. Previous studies report highly efficient production of solar steam in fluids with gold nanoparticles. In this article, we establish the process in nanofluids with less expensive carbon black (CB) and iron oxide (IO) nanoparticles (NP). Screening the concentration of nanoparticles, we tailor the nanofluids to reach the efficiency maxima: 66% at 3% wt. (CBNP) and 75% at 10% wt (IONP); the steam was superheated up to 10 K (CBNP) and 16 K (IONP). It was also discovered that the IONPs-generated steam was contaminated with nanoparticles. In addition to experimental results, we have developed an empirical model of photo-thermal steam generation in nanofluids. The model agrees well with the experiments. D. Navilan"Photothermal Boiling in Aqueous Nanofluids" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-2 | Issue-5 , August 2018, URL: http://www.ijtsrd.com/papers/ijtsrd17114.pdf http://www.ijtsrd.com/physics/nanotechnology/17114/photothermal-boiling-in-aqueous-nanofluids/d-navilan
This document summarizes an evaluation of an upcoming version of the Copernicus Atmosphere Monitoring Service's (CAMS) global production system. The evaluation compares the operational run (o-suite) to an experimental run (e-suite) that has a higher horizontal resolution and will replace the o-suite. The evaluation found no significant differences between the runs for most species, like ozone and carbon monoxide profiles and surface concentrations. However, improvements were seen for surface ozone and nitrogen dioxide in areas with complex terrain or high pollution, likely due to the increased resolution. Slight degradation was found for dust aerosols in Central Asia in the new run. The e-suite will become operational next week with full evaluation results published
This document summarizes research on using electrodeposited manganese dioxide (MnO2) coatings on porous carbon substrates for capacitive deionization (CDI) applications. Two carbon substrates with different surface areas and morphologies were coated with MnO2 using galvanostatic and cyclic voltammetric deposition. Characterization of the coated electrodes found mixed MnO2 phases present. Testing in half-cell configurations showed that maximum ion uptake per mass was not necessarily optimal for practical CDI applications, where performance per electrode area is more important. The results suggest the structure and deposition method can impact how effectively the electrode volume participates in ion removal reactions.
This project aimed to develop graphene oxide (GO) membranes for water filtration by synthesizing GO flakes using two Hummer's methods, characterizing the flakes, selecting a substrate, depositing GO on it, and testing salt rejection. Polyethersulfone (PES) was chosen as the substrate. The second synthesis method yielded more oxidized and amorphous GO flakes based on characterization. GO was deposited on plasma-treated PES using a dead-end cell. Diffusion testing found the homemade GO membrane rejected 75.6% of salts compared to 94.2% for a commercial membrane, demonstrating potential for economical water treatment.
A Novel Method of Synthesizing Graphene for Electronic Device ApplicationsMariana Amorim Fraga
This document describes a novel method for synthesizing graphene using a thermal decomposition process. Silicon carbide (SiC) thin films were grown on silicon wafers covered with an aluminum nitride buffer layer, then exposed to CO2 laser beam heating without vacuum or controlled atmosphere. This caused the SiC films to thermally decompose into graphene. The properties of the resulting graphene, such as structure, morphology, and electrical resistance, were investigated using various characterization techniques and found to depend on the applied laser energy density. The graphene exhibited properties suitable for applications in electronic devices.
This document discusses nanoporous graphene (NPG) fabrication methods, ion and gas permeation mechanisms through NPG, and presents preliminary experimental results. It summarizes that NPG has potential for desalination and gas separation due to high permeability from atomic thickness and strength to withstand high pressures. Permeation is dependent on pore size and functionalization, which can be used to control selectivity. The author's project aims to experimentally investigate ion selectivity of graphene nanopores and verify computational results by measuring ionic conductivity across graphene membranes using a setup that seals nanopores with graphene. Representative results show graphene seals 150nm pores and ion-voltage curves with and without sealed pores.
As the author ages, they find more fascination in the arrival of spring each year and the natural beauty of rebirth it brings. They have discovered an appreciation for taking time to experience each moment and sense of wonder in the world, and a hope that more springs will continue to come as they grow older.
Multiple Contract Pharmacies in a Disproportionate Share Hospital Systemanthonylesser
This document summarizes a presentation about the Harris County Hospital District's (HCHD) use of multiple contract pharmacies through an Alternative Methods Demonstration Project (AMDP). HCHD operates three major hospitals and 15 ambulatory pharmacies serving over 1.6 million outpatient visits per year. It applied for an AMDP in 2006 to use an off-site automated central fill pharmacy in Fort Worth to increase efficiency and patient access. The central fill pharmacy now fills 70% of prescriptions using a closed formulary. HCHD realized operational efficiencies, improved wait times, and was able to reduce staff while maintaining compliance.
Competency Based E Portfolios Slide Share Final March 26 2010Greg Williams
This was a presentation by Dr. Greg Williams at the eLearning Guild's "Learning Solutions" conference in Orlando, FL on March 26, 2010. For more information on the presenter visit www.gregwilliams.net
Powerpoint presentation from Asia Society/CCSSO symposium: International Perspectives on U.S. Education Policy and Practice: What Can We Learn from High Performing Nations?
El documento presenta una serie de instrucciones absurdas encontradas en etiquetas de productos que sugieren que la inteligencia humana está disminuyendo. Algunas de las instrucciones incluyen advertencias sobre no usar jabón como jabón normal, descongelar comida congelada antes de comerla, y no dar vuelta a un envase. Esto lleva al autor a concluir que la raza humana se dirige inevitablemente hacia la estupidez basado en la necesidad de advertir sobre conceptos obvios.
The document discusses butterfly bush and edging. Butterfly bush is a flowering shrub that grows 5 to 10 feet tall, blooms in lavender, pink or purple, and attracts butterflies and birds. It can become invasive and needs pruning every winter. The document also discusses different types of edging for gardens, including plastic, dug, stone, and poured edging. Edging creates a sharp line between gardens and lawns and keeps grass and weeds from growing into garden beds.
This document describes research into using pulsed anodic arc discharges to synthesize carbon nanomaterials. Pulsed arcs with frequencies of 1-5 Hz and a 10% duty cycle were generated between graphite electrodes in a helium atmosphere. Plasma parameters like electron density (1016-1017 m-3) and temperature (0.5-2.0 eV) were measured. Carbon nanostructures like graphene nanoplatelets and carbon nanotubes were deposited on the cathode. Pulsed arcs showed higher peak currents than steady DC arcs but did not reach steady state levels. This pulsed method could improve control over carbon nanomaterial synthesis compared to conventional DC arcs.
Paper spray ionization was paired with a mechanical-gate ion mobility spectrometer to detect herbicide ions. The ion mobility spectrometer contained a drift tube with stainless steel rings and resistors, a detector, and a mechanical gate. Paper spray ionization used high voltage applied to filter paper wetted with analyte solution to create ions. Blank samples consistently produced two peaks likely from protonated water and methanol clusters. Samples with the herbicide prometon consistently showed three peaks, including one from protonated prometon clusters. Aperture grids were investigated to reduce peak width but lowered signal. Future work will optimize peak resolution and identification.
This document describes a method for synthesizing nitrogen-doped porous graphitic carbon materials for use as electrodes in supercapacitors. The method involves polymerizing aniline in the presence of ferric chloride, followed by high-temperature treatment and chemical activation to produce a 3D porous structure. The novel carbon material demonstrated a high specific capacitance of 300 F/g as an electrode in aqueous electrolyte. Further characterization showed the material had a surface area of over 1200 m2/g after activation.
Importance of plasma conditions for vertically aligned carbon nanowalls synth...Marcel Mesko
This document discusses the importance of plasma conditions for vertically aligned carbon nanowall synthesis. It summarizes the plasma concepts and fundamentals relevant for nanofabrication. It also examines the effects of bombarding ions and electric fields on the alignment mechanisms of carbon nanotubes and nanowalls during plasma-assisted growth. Furthermore, it explores the use of direct and remote plasma processes to reduce graphite oxide materials.
The document summarizes a hyphenated technique combining capillary electrophoresis (CE) and inductively coupled plasma mass spectrometry (ICP-MS) for elemental speciation analysis. It discusses the CE-ICP-MS instrumentation including interface designs, applications to analyze arsenic and chromium species in preserved wood and soil, and preliminary results examining interface configurations and gas flow rates.
1) The SPARC-EBIT is a new electron beam ion trap (EBIT) installed at GSI for testing as an injector for HITRAP and as a charge breeder.
2) Current experiments are characterizing the SPARC-EBIT and testing its capabilities for ion production, x-ray spectroscopy, and charge breeding.
3) Future plans include using the SPARC-EBIT as an offline injector for HITRAP and developing it as a charge breeder for the MATS facility.
This study evaluated using an electrocoagulation process with solar power to remove excess phosphorus from surface waters. The process uses aluminum electrodes and an applied electric current to dissolve the metal into the water, facilitating the removal of phosphates through precipitation and coagulation. Testing of the laboratory scale reactor showed it was capable of removing 99% of phosphates from synthetic water, surface water, and treated wastewater. The removal efficiency increased with higher conductivity and more applied power. Testing also demonstrated the system could reduce total and fecal coliform bacteria by 90-99% with increased voltage.
The document summarizes research on synthesizing graphene via chemical vapor deposition for use in supercapacitor electrodes. It describes using CVD to deposit graphene on copper foil substrates by flowing methane and hydrogen gases into a heated furnace. Experiments varied the hydrogen flow rate and growth time, finding that higher hydrogen levels and shorter times produced higher quality mono-layer graphene, as shown through Raman spectroscopy analysis. The document also explores electropolishing copper substrates and transferring graphene to other substrates for use in supercapacitors.
International Journal of Research in Engineering and Science is an open access peer-reviewed international forum for scientists involved in research to publish quality and refereed papers. Papers reporting original research or experimentally proved review work are welcome. Papers for publication are selected through peer review to ensure originality, relevance, and readability.
The process of photo thermal evaporation in nanofluids finds promising applications in solar energetics, medicine and process technology. Previous studies report highly efficient production of solar steam in fluids with gold nanoparticles. In this article, we establish the process in nanofluids with less expensive carbon black (CB) and iron oxide (IO) nanoparticles (NP). Screening the concentration of nanoparticles, we tailor the nanofluids to reach the efficiency maxima: 66% at 3% wt. (CBNP) and 75% at 10% wt (IONP); the steam was superheated up to 10 K (CBNP) and 16 K (IONP). It was also discovered that the IONPs-generated steam was contaminated with nanoparticles. In addition to experimental results, we have developed an empirical model of photo-thermal steam generation in nanofluids. The model agrees well with the experiments. D. Navilan"Photothermal Boiling in Aqueous Nanofluids" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-2 | Issue-5 , August 2018, URL: http://www.ijtsrd.com/papers/ijtsrd17114.pdf http://www.ijtsrd.com/physics/nanotechnology/17114/photothermal-boiling-in-aqueous-nanofluids/d-navilan
This document summarizes an evaluation of an upcoming version of the Copernicus Atmosphere Monitoring Service's (CAMS) global production system. The evaluation compares the operational run (o-suite) to an experimental run (e-suite) that has a higher horizontal resolution and will replace the o-suite. The evaluation found no significant differences between the runs for most species, like ozone and carbon monoxide profiles and surface concentrations. However, improvements were seen for surface ozone and nitrogen dioxide in areas with complex terrain or high pollution, likely due to the increased resolution. Slight degradation was found for dust aerosols in Central Asia in the new run. The e-suite will become operational next week with full evaluation results published
This document summarizes research on using electrodeposited manganese dioxide (MnO2) coatings on porous carbon substrates for capacitive deionization (CDI) applications. Two carbon substrates with different surface areas and morphologies were coated with MnO2 using galvanostatic and cyclic voltammetric deposition. Characterization of the coated electrodes found mixed MnO2 phases present. Testing in half-cell configurations showed that maximum ion uptake per mass was not necessarily optimal for practical CDI applications, where performance per electrode area is more important. The results suggest the structure and deposition method can impact how effectively the electrode volume participates in ion removal reactions.
This project aimed to develop graphene oxide (GO) membranes for water filtration by synthesizing GO flakes using two Hummer's methods, characterizing the flakes, selecting a substrate, depositing GO on it, and testing salt rejection. Polyethersulfone (PES) was chosen as the substrate. The second synthesis method yielded more oxidized and amorphous GO flakes based on characterization. GO was deposited on plasma-treated PES using a dead-end cell. Diffusion testing found the homemade GO membrane rejected 75.6% of salts compared to 94.2% for a commercial membrane, demonstrating potential for economical water treatment.
A Novel Method of Synthesizing Graphene for Electronic Device ApplicationsMariana Amorim Fraga
This document describes a novel method for synthesizing graphene using a thermal decomposition process. Silicon carbide (SiC) thin films were grown on silicon wafers covered with an aluminum nitride buffer layer, then exposed to CO2 laser beam heating without vacuum or controlled atmosphere. This caused the SiC films to thermally decompose into graphene. The properties of the resulting graphene, such as structure, morphology, and electrical resistance, were investigated using various characterization techniques and found to depend on the applied laser energy density. The graphene exhibited properties suitable for applications in electronic devices.
This document discusses nanoporous graphene (NPG) fabrication methods, ion and gas permeation mechanisms through NPG, and presents preliminary experimental results. It summarizes that NPG has potential for desalination and gas separation due to high permeability from atomic thickness and strength to withstand high pressures. Permeation is dependent on pore size and functionalization, which can be used to control selectivity. The author's project aims to experimentally investigate ion selectivity of graphene nanopores and verify computational results by measuring ionic conductivity across graphene membranes using a setup that seals nanopores with graphene. Representative results show graphene seals 150nm pores and ion-voltage curves with and without sealed pores.
As the author ages, they find more fascination in the arrival of spring each year and the natural beauty of rebirth it brings. They have discovered an appreciation for taking time to experience each moment and sense of wonder in the world, and a hope that more springs will continue to come as they grow older.
Multiple Contract Pharmacies in a Disproportionate Share Hospital Systemanthonylesser
This document summarizes a presentation about the Harris County Hospital District's (HCHD) use of multiple contract pharmacies through an Alternative Methods Demonstration Project (AMDP). HCHD operates three major hospitals and 15 ambulatory pharmacies serving over 1.6 million outpatient visits per year. It applied for an AMDP in 2006 to use an off-site automated central fill pharmacy in Fort Worth to increase efficiency and patient access. The central fill pharmacy now fills 70% of prescriptions using a closed formulary. HCHD realized operational efficiencies, improved wait times, and was able to reduce staff while maintaining compliance.
Competency Based E Portfolios Slide Share Final March 26 2010Greg Williams
This was a presentation by Dr. Greg Williams at the eLearning Guild's "Learning Solutions" conference in Orlando, FL on March 26, 2010. For more information on the presenter visit www.gregwilliams.net
Powerpoint presentation from Asia Society/CCSSO symposium: International Perspectives on U.S. Education Policy and Practice: What Can We Learn from High Performing Nations?
El documento presenta una serie de instrucciones absurdas encontradas en etiquetas de productos que sugieren que la inteligencia humana está disminuyendo. Algunas de las instrucciones incluyen advertencias sobre no usar jabón como jabón normal, descongelar comida congelada antes de comerla, y no dar vuelta a un envase. Esto lleva al autor a concluir que la raza humana se dirige inevitablemente hacia la estupidez basado en la necesidad de advertir sobre conceptos obvios.
The document discusses butterfly bush and edging. Butterfly bush is a flowering shrub that grows 5 to 10 feet tall, blooms in lavender, pink or purple, and attracts butterflies and birds. It can become invasive and needs pruning every winter. The document also discusses different types of edging for gardens, including plastic, dug, stone, and poured edging. Edging creates a sharp line between gardens and lawns and keeps grass and weeds from growing into garden beds.
Using FME to Build an Enterprise GeodatabaseSafe Software
A recent project at the City of Barrie involved building a Geodatabase for Land Parcel Base and Planning datasets. This Geodatabase is a foundation that is part of an overall plan to build an Enterprise GIS Server that is linked to multiple business systems and web applications. The presentation will provide an overview of the project approach, and discuss some of the challenges and solutions getting 12 large CAD drawings into the target data model using FME.
The International Society for Professional Innovation Management (ISPIM) is a global network of researchers, practitioners, and policymakers interested in innovation management. Founded in 1983, ISPIM organizes annual conferences and symposiums to facilitate networking and knowledge sharing around innovation. Recent challenges included making events more relevant and improving networking opportunities between academics and corporate delegates. ISPIM looks for centrally located venues that can accommodate hundreds of attendees, include facilities for breakout sessions, and support social functions in the evenings.
The document summarizes proposed changes to the Indian Income Tax Act of 1961 as presented in a talk on March 3rd, 2010. Some key changes include:
- Introduction of a new tax slab structure for individuals with rates from 0-30% depending on income level.
- Increase in surcharge on income tax for domestic companies with income over 1 crore from 7.5% to 10%.
- Expansion of the definition of "charitable purpose" and changes to provisions around cancellation of trusts.
- Changes to depreciation, research and development deductions, and provisions around carried forward losses for companies converting to LLPs.
- Increased thresholds for tax audit from 40 to 60
The document lists various restaurants that won Daily Press Choice Awards in 2009 in different categories such as Asian Buffet, BBQ, Breakfast, Brunch, Chicken Salad, Coffee House, Day Spa Restaurant, Diner, Diverse Menu, Family Restaurant, French Restaurant, Frozen Dessert, Frozen Yogurt, Full Service Chinese Restaurant, Greek Restaurant, Hookah Lounge, Hot Dog, Ice Cream, Irish Pub, Italian, Kept Secret, Latin Restaurant/Lounge, Local Lunch, Location For A Fundraiser, Lounge, Martini Bar, Meatball Sub, Mexican, Mexican Fajitas, New Restaurant, Oyster Bar/Seafood, Pizza, Prime Rib, Restaurant, Ribs, Sea
Presentation given at Minnesota Council on Nonprofits 2010 Nonprofit Technology and Communications Conference - March 24, 2010. This was an interactive session where the participants brainstormed technology budgeting ideas for nonprofits, and created this list of tips: http://bit.ly/nptechbudgetingtips
This document discusses using the MXML compiler (mxmlc) to compile Flex projects from the command line rather than within Flex Builder. It provides an example command to compile a FlexMXML file located in the user's Documents folder. Additional command line arguments are also demonstrated, such as specifying the output SWF file location and adding library paths. The document recommends adding the Flex SDK bin directory to the system PATH environment variable so mxmlc can be called directly from the command line without specifying the full SDK path.
The document provides an introduction to LinkedIn and guidance on setting up a profile. It recommends signing up for a free or paid LinkedIn account, designing your profile like a marketing piece with a full summary and specialties section, adding contact information and keywords, and building your network by joining groups and uploading contacts to find more opportunities.
Ms. Olga MALASENKO is a postgraduate student in international hotel management with experience in business administration and founding her own ambulatory care company in Estonia from 2010 to 2016. She is looking for a management internship position and has a background in interior design, spatial design, interpretation, and volunteering in hospitality.
Microscopy microanalysis microstructures_the european physical journal_applie...Andrea Sentimenti
This document describes a method for fabricating nano-sized carbon tips in a scanning electron microscope (SEM) using controlled carbon contamination. Key steps include: using a 30kV beam for highest contamination rate; smallest spot size (~5nm); stable, well-focused beam; and a carbon block nearby to increase carbon concentration. Tips with 10° aperture and ~5nm tip are produced in under 60 seconds. Successive focusing during growth produces tips shaped like stacked cones rather than a single paraboloid. The tips are used as probes in atomic force microscopy, achieving higher resolution than conventional probes due to their small size and shape. They are also used as field emitters for electron guns due to their nanoscale size and
A perovskite solar cell is a type of solar cell which includes a perovskite structured compound, most commonly a hybrid organic-inorganic lead or tin halide-based material, as the light-harvesting active layer.
This document summarizes research into using laser excitation of cesium ions to enhance the performance of thermionic energy converters (TECs). The researchers have developed a particle-in-cell model of a planar diode discharge to simulate TEC operation and are using it to model the effects of laser excitation on current-voltage characteristics. They have also designed a laboratory test cell to experimentally validate the effects of laser excitation on TEC performance. Initial results suggest laser excitation could substantially improve TEC current density and efficiency over conventional ignited or triode configurations.
This document summarizes research into using laser excitation to enhance the production of cesium ions in thermionic energy converters (TECs). The researchers have developed a particle-in-cell model of a planar diode discharge to simulate TEC performance with and without laser ionization. They have also designed a laboratory test cell to experimentally validate the effect of laser excitation on TEC current-voltage characteristics. Future work will include refining the models, procuring parts for the test cell, and conducting experimental studies to analyze how laser excitation can increase TEC efficiency and be used in energy systems to reduce carbon emissions.
This document summarizes research into using laser excitation to enhance the production of cesium ions in thermionic energy converters (TECs). The researchers have developed a particle-in-cell model of a planar diode discharge to simulate TEC performance with and without laser ionization. They have also designed a laboratory test cell to experimentally validate the effect of laser excitation on TEC current-voltage characteristics. Future work will include refining the models, procuring parts for the test cell, and conducting experimental studies to characterize optimized TEC performance with optical modulation. The goal is to increase TEC efficiency for applications in solar and combustion energy systems to reduce greenhouse gas emissions.
This document summarizes research into using laser excitation of cesium ions to enhance the performance of thermionic energy converters (TECs). The researchers have developed a particle-in-cell model of a planar diode discharge to simulate TEC operation and are using it to model the effects of laser excitation on current-voltage characteristics. They have also designed a laboratory test cell to experimentally validate the effects of laser excitation on TEC performance. Initial results suggest laser excitation could substantially improve TEC current density and efficiency over conventional ignited or triode configurations.
Optimal Generation of 254nm ultraviolet radiationIOSR Journals
Abstract: The science of the application of 254nm UV from mercury doped glow discharge tubes has been a major topic since Johann Ritter discovered UV via its chemical inducing reactions in 1801 and Niels Finsen’s 1860 work on UV therapy in treating rickets. In 1857 Siemens AG patented UV254nm creation via filamentary discharge, subsequently widely used for ozone production. By 1932 the Coblentz Congress had defined the three regions of the UV action spectrum. This paper presents the science of a new design for a sterilizer module fabricated from extruded, recycled aluminium. This novel design achieves better than D10 performance using six UV tubes per module driven by three electronic ballasts drawing a total current of only 1.26 amps at 240V single phase. This module delivers more than 45,000 microwatts per square centimetre of 254nm UV which sterilises one litre per second in a module with a dwell time of 1.6 seconds in a design with less than 0.5 bar pressure drop across each module. This system takes the electrical efficiency of 254 UV generation from less than 25% to more than 92% as measured by an NPL-traceable calibration against a current industry standard. Since 254nm UV generating tubes are also the basis of fluorescent lighting this new work on optimising the generation of 254nm UV also has application worldwide to improved efficiency of fluorescent tube electrical lighting, because we have shown that most of the fluorescent lamps operating today (particularly the T8 1” diameter) are running at less than 25% efficiency as opposed to the over 92% which is possible with the methods we describe. The work reported here shows that the Townsend equation for electron transport in glow discharge plasmas is not adequate since it does not address either plasma diameter or plasma drive frequency both of which fundamentally alter the electron energy transfer efficiencies to mercury atoms in the plasma.
Low Cost Synthesis of Single Walled Carbon Nanotubes from Coal Tar Using Arc ...IOSRJAP
There are various methods such as arc discharge, laser ablation, chemical vapour deposition (CVD), template-directed synthesis for the growth of CNTs in the presence of catalyst particles. The production of carbon nanotubes in large quantities is possible with inexpensive coal as the starting carbon source by the arc discharge technique. It is found that a large amount of carbon nanotubes of good quality can be obtained in the cathode deposits in which carbon nanotubes are present in nest-like bundles. For more than two decades, now, there has been extensive research on the production of carbon nanotubes (CNT) and optimization of its manufacture for the industrial applications. It is believed that they are the strong enough but most flexible materials known to mankind. They have potential to take part in new nanofabricated materials. It is known that, carbon nanotubes could behave as the ultimate one-dimensional material with remarkable mechanical properties. Moreover, carbon nanotubes exhibit strong electrical and thermal conducting properties. This paper primarily concentrates on the optimising such parameters related to the mass production of the product. It has been shown through Simplex process that based on the cost of the SWNT obtained by the arc discharge technique, the voltage and the current should lie in the range of 30 - 42 V and 49 - 66 A respectively. Any combination above the given values will lead to a power consumption cost beyond the final product cost, in turn leading to infeasibility of the process. Strong expectations exist for future use of carbon nanotubes as composite materials in a large number of industries. Production cost and control of the purity and properties of such materials will influence the impacts nanotubes on the chemical, computer and construction industries. Coal properties in this case are also important. Weak bonds and mineral matter in the coal play an important role in the formation of the nanotubes
Perovskite Solar Cells
a short general overview presentation
hadi maghsoudi
device structure
crystal structure
preparation synthesis method
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Estimation of flow accelerated corrosion (fac) in feeder pipes using cf dd so...Alexander Decker
This article summarizes a study on estimating flow accelerated corrosion (FAC) in feeder pipes of a nuclear reactor using computational fluid dynamics (CFD) software. The study had two objectives: 1) perform CFD analysis of a modeled feeder pipe using Fluent software to estimate maximum wall thinning, and 2) design an experimental setup to study FAC at low temperatures. The CFD analysis estimated a maximum wall thinning rate of 1.1 mm/year in a feeder pipe bend. Experimental tests on mild steel coupons in water at 90°C found corrosion rates up to 1.63 g/cm2/year but no evidence of FAC below this temperature.
This document describes current injection induced terahertz emission from 4H-SiC p-n junctions. The emission is attributed to intracenter optical transitions in nitrogen donor centers in the n-type region of the SiC p-n junction. When a current is injected, non-equilibrium carriers are injected into the n-region, initiating radiative transitions within the nitrogen donor centers. Emission peaks were observed that match the known energy levels of optical transitions in nitrogen donors. At 100 K and 300 mA, an output power of 58 μW was measured from a 3 mm2 device surface. This demonstrates that terahertz emitting devices can be made from simple SiC p-n junction structures with reasonable output powers and
Production of CH4 and C2 hydrocarbons by axial and radial pulse H2/CO2 discha...theijes
Production of methane CH4 from a mixture gas of carbon dioxide CO2 and hydrogen H2 has been established by two types of pulse discharges. One is an axial discharge with a use of thin pair Ni wire electrodes separated by a narrow gap, and the other is a coaxially radial discharge with a use of inner rod and outer tube electrodes made of stainless steel (SUS). The former provides an intense gap discharge, while the latter provides a gentle discharge in the annular region. Decomposition of CO2 is enhanced in the former case when Ni (nickel) mesh disc electrode is placed behind the gap. Ni is known as catalysis. When the radial discharge proceeds in a closed gas system, 2C hydrocarbons such as ethane and ethylene are generated in case that a cylindrical mesh electrode made of Ni is attached to the powered SUS tube electrode. Both of the CH4 production and the energy efficiency for CH4 production are enhanced in case of Ni mesh electrodes, without a use of additional heating for the Ni catalysis. Synergy effect of plasma and Ni catalyst is observed
The document summarizes a study that investigated the spark plasma sinterability and dry sliding wear resistance of tungsten carbide (WC) densified with cobalt (Co), cobalt-nickel (Co+Ni), and cobalt-nickel-chromium (Co+Ni+Cr) binders. Dilatometric spark plasma sintering tests showed that partial substitutions of Co with Ni or Ni+Cr decreased sinterability, with Ni+Cr having a greater negative effect. However, isothermal sintering under pressure was affected little by the substitutions. Testing found the materials were very resistant to dry sliding wear, with WC-Co+Ni+Cr exhibiting the greatest hardness and wear resistance due to its higher
International Journal of Engineering Research and Development (IJERD)IJERD Editor
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Potential enhancement of thermoelectric energy conversion in cobaltite superl...Anastasios Englezos
This document is a master's thesis submitted by Tasos Englezos investigating the potential enhancement of thermoelectric energy conversion in cobaltite oxide superlattices. The thesis aims to grow superlattices composed of alternating layers of NaxCoO3 and Ca3Co4O9 using pulsed laser deposition, as both materials show promise for thermoelectric applications but also have limitations. Characterization of the superlattices shows the structures maintain crystalline coherence while electrical and thermal properties are preserved at a good level. Further measurements of thermal conductivity are needed to determine if the superlattice approach reduces thermal conductivity and thereby improves thermoelectric efficiency in these cobaltite oxides.
Federico Capasso is a designer of new materials using nanotechnology. Some of his most important work includes developing quantum cascade lasers and flat optics. Quantum cascade lasers emit laser light by passing current through nanometer-thick layers, allowing the laser wavelength to be tailored. This enabled numerous applications in chemical sensing, medical imaging, and more. Flat optics uses metasurfaces to refract light instead of lenses, opening opportunities to replace lenses in many applications. Capasso's work has advanced fields like photonics, materials science, and biomedical technologies.
Horning’s group in the 1970’s developed atmospheric pressure ionization (API) mass spectrometry (MS), but it was electrospray ionization that drove the commercialization of API-MS as a liquid introduction technology. The utility of gaseous introduction of volatile compounds into an API source and new developments in GC-API/MS and ASAP-MS will be discussed along with the newly discovered matrix-assisted ionization technology that allows ionization of low and high mass compounds on API instruments without use of a laser, high voltage, or even heat.
The document discusses a technique developed by NASA to use thermographic imaging and a scanning line heat source to detect and quantify material loss from corrosion in boiler water-wall tubing. The technique involves moving a thermal line source across the tubing surface and using an infrared imager behind it to capture temperature variations induced at the surface. Quantitative images can then be reconstructed to show thickness changes from corrosion. The technique provides a significant improvement in inspection speed over conventional ultrasonic methods for large structures like boiler water-walls. Experimental results on steel samples with fabricated thinning show the technique can successfully detect and measure material loss.
Modeling and Optimization of Cold Crucible Furnaces for Melting MetalsFluxtrol Inc.
http://fluxtrol.com
Cold Crucible Furnaces (CCFs), widely used in multiple special applications of
melting metals, oxides, glasses and other materials [1], are essentially 3D devices and their modeling is a complicated task. Multiple studies of CCFs have been made for their
optimization, but their electrical efficiency is still low; for metals approximately 25-30% andeven lower. Fluxtrol, Inc., made an extensive study of electromagnetic processes of CCFs using computer simulation and laboratory tests. This study showed that electrical efficiency of CCFs may be strongly improved by means of optimal design of the whole system with use of magnetic flux controllers. Theoretical results had been confirmed by laboratory tests on mockups and by industrial tests with real melting processes. The presentation contains a description of the computer modeling procedure and major findings. They form a basis for optimal design of electromagnetic systems of CCFs.
The document summarizes a study that demonstrated the ability to tune the size of large-diameter, few-walled nitrogen-doped carbon nanotubes (N-CNTs) from 50-150 nm by varying the transition metal (TM) used during synthesis. Fe produced the largest tubes, followed by Co and Ni, while Mn resulted in a clot-like morphology. Electrocatalytic activity for the oxygen reduction reaction (ORR) followed the trend Fe > Co > Ni > Mn. Fe-derived N-CNTs exhibited the highest surface area and nitrogen incorporation, contributing to their high ORR activity. This work provides a new route for developing advanced nonprecious metal catalysts by controlling carbon nanot
1. AN ION SOURCE FOR THE HVEE 14C ISOTOPE RATIO MASS SPECTROMETER
FOR BIOMEDICALAPPLICATIONS
DIRKJ. W. MOUS, WIM FOKKER, REIN VANDENBROEK, RON KOOPMANS
High Voltage Engineering Europa B.V., PO Box 99, 3800 AB Amersfoort, The Netherlands
CHRISTOPHER BRONKRAMSEYI andR. E. M. HEDGESI
Oxford Radiocarbon Accelerator Unit, Oxford University, 6 Keble Road, Oxford OX13QJ
United Kingdom
ABSTRACT. During the past two decades, accelerator mass spectrometry (AMS) has allowed major developments in many
areas of geosciences and archaeology. In the near future, AMS should realize a similar potential in the field of biomedical
research, leading ultimately to clinical applications. For such applications, the required instrument differs significantly from
thatpresently used in the field of 14C dating. Whereas the needed accuracy and sensitivity is more than an order ofmagnitude
less demanding than that for present state-of-the-art14C instrumentation, the widespread acceptance of 14C AMS in biomed-
ical research will require AMS spectrometers that are small, simple to operate and capable of handling CO2samples. In order
to satisfy these demands, HVEE has developed a compact 14C AMS spectrometer dedicated to biomedical research. The
instrument consists of a compact accelerator with a footprint of 2.25 x 1.25 m and an ion source that features direct CO2
acceptance and optimal user friendliness. Having previously described the layout and design of the accelerator, we here dis-
cuss progress on the accelerator and present the design and first results of the CO2 ion source.
INTRODUCTION
In the past two decades, AMS has developed into a mature scientific tool for a variety of applica-
tions in the geosciences and archaeology. The usefulness ofAMS has been recognized in other dis-
ciplines as well, notably biomedical research (Davis et al. 1990; Davis 1994), as demonstrated by an
exponential increase in the number of contributions in this field at recent AMS conferences in Can-
berra-Sydney (Fifield et a1.1994) and Tucson (Jull, Beck and Burr 1997).
The required instrumentation for biomedical research differs significantly from that presently used
in the field of 14C dating. The use ofAMS instrumentation withinthe biomedical community is pres-
ently handicapped by the size of existing systems and their need for expensive support personnel;
widespread acceptance will require small AMS spectrometers that need little or no maintenance and
that are easy to operate. Size reduction of the instrument can be achieved by sacrificing sensitivity
and accuracy, since these specifications are at least one order of magnitude less demanding in bio-
medical research. Throughput requirements are an order of magnitude higher, however.
The present AMS technique relies on a laborious graphitization procedure that is unknown to the
biomedical community. The introduction of AMS instrumentation to this community would be
eased by the availability of ion sources that directly accept C02, enabling direct interfacing with a
CHN analyzer or a gas chromatograph.
HVEE has developed a compact AMS spectrometer dedicated to biomedical research that over-
comes the shortcomings of the presently available AMS instruments. With a footprint of2.25 x 1.25
m, it is easy to operate and capable of analyzing CO2 samples. Previously (Mows et al. 1997) we
reported on the design and layout of the instrument, whose accuracy and throughput have yet to be
fully characterized. Here we discuss progress on the system and present the development and first
results of a compact cesium-type sputter source that directly accepts CO2.
1These authors were exclusively involvedin the design and development of the CO2 ion source.
Proceedings ofthe 16th International 14C Conference, edited by W. G. Mookand J. van derPlicht
RADIOCARBON, Vol. 40, No. 1, 1998, P. 283-288 283
2. 284 D. J. W. Mous et al.
THE CO2 ION SOURCE
The design of the CO2 ion source results from cooperation between HVEE and Oxford University.
Its design is based on that of the OXGIS source developed at Oxford (Bronk 1990), with improve-
ments seeking to minimize memory effects and optimize user friendliness. The operation character-
istics of the ion source are reflected in the following features:
acceptance ofboth graphite samples and CO2 samples admitted from ground potential;
an easily exchanged 50-sample carousel;
source embodiment at ground potential ensuring easy and safe operation;
almost complete absence ofradiation hazard as a result of a stainless-steel source embodiment;
optimal vacuum conditions for low memory effects;
easy, quick source maintenance via sideways disassembly of the source-head.
A schematic layout ofthe Cs sputter-type ion source is shown in Figure 1. Its principle of operation
is well understood and described extensively in the literature (e.g., Alton 1990). In this section we
concentrate on the technical aspects ofthe new source design.
»-360 l/s TURBINE PUMP
CAROUSEL
COOLED
TARGET HOLDER
ION BEAM
iR
H. CARRIER
C02
SOURCE HEAD FLANGE
Cs RESERVOIR
PRESSURE RELIEF HV INSULATION TUBE CAPILLARY SOURCE HEAD
Fig. 1. Schematic layout ofthe CO2 ion source
The stainless-steel source embodiment, including carousel, is at ground potential during operation,
avoiding the necessity ofa large isolation cage, thereby reducing the space requirements of the total
assembly. Isolation of the extraction and target voltage is achieved by insulators within the source
embodiment (Fig. 1). All high-voltage connections to the source, including the Cs reservoir, the CO2
feed tube and the cooling lines, are brought together on the source-head insulation flange, keeping
the space needed for external high-voltage isolation to a minimum. The source-head (Fig. 2) can be
pulled sideways from the source embodiment, making maintenance easy and quick.
A 360 L sturbomolecular pump is directly mounted on the source embodiment, just above the
source-head, providing optimal pumping speed in the source area. This fulfills an important condi-
3. Ion Sourcefor the HVEE Mass Spectrometer 285
I? Ifl M
P°l+tt 11 p
t`31
Fig. 2. Photograph ofthe source-head
tion for low memory in the case of CO2 targets, which is of paramount importance for biomedical
applications, where the 14C content of a sample can vary by many orders of magnitude.
The sample carousel can accommodate up to 50 samples and is isolated from the source by a 100-
mm diameter gate-valve, ensuring good vacuum conditions at the carousel at all times. A pneumat-
ically operated cylinder transports the sample under investigation into the ion source.
The source accepts graphite as well as CO2 samples. Solid graphite sample material is pressed in a
target holder in a similar manner as is done in most modern AMS laboratories. CO2 samples can be
admitted into the ion source from ground potential. A He carrier ofca. 1 sccm transports the CO2 via
an isolation tube and a stainless-steel capillary into the ion source (Fig. 1). Here, the CO2 is absorbed
on the surface ofa titanium target, where it is sputtered and ionized to form a negative carbon beam.
During gas admission, the vacuum level in the source is maintained at ca. 1 x 10-5 mbar.
OPERATION AND FIRST RESULTS
The source is operated at a target potential of6 kV and 19 kV extraction, giving a 25 keV ion energy.
Analyzed 12C currents from graphite samples were measured at between 50 and 100 .tA, with mod-
erate Cs supply into the ion source. No attempts have been made to push the source to its limits, but
currents well in excess of 100µA should be achievable. Figure 3 shows the analyzed 12C- current
for different graphite samples as a function of time. After target insertion, the 12C current rises
quickly, stabilizing within ca. 30 s. Furthermore, it can be seenfrom the figure that the sample trans-
fer time (for neighboring samples) is ca. 7 s. During sample exchange (t = -55 s in Fig. 3), a few,uA
of 12C-current is still present. This current probably results from the distorted ion optics ofthe sput-
tering Cs beam due to the absence ofthe targetin the source and does not reflect actual source back-
ground.
4. 286
50
40
30
20
10
0
----------- --------------------- ---------- ----------
I I
^_--'___--L- _---1--_-------L'-'--'--'-1 __ -------- J
-
------- J-----
-----f----------f----------t-------------------- ------- -------
-___----__L--___---_-1--_---_--_-__-__-__-J __--_-_ - ------
sets;
--- I
;7
__--___--_r____--____T____----__T--__-_-_--1 ------- -1_-_-_
-
------L----------L'---------L'-_----------------- ------- -J-__
-
-------'r----------'r----------' -------' ------ ------ ----
0 10 20 30 40 50 60 70
Time (seconds)
Fig. 3. Analyzed 12C- ion source current as a function of time for two different graphite samples
The Cs spot size on the target was measured at ca. 0.8 mm in diameter, which corresponds reason-
ably well to the design value of 0.6 mm. The emittance ofthe source for a 50µA 12C beam was mea-
sured at ca. 6 mm mrad MeV- 5.
Exchanging of the carousel, which houses 50 targets, is easy; pump-down takesca. 5 min before the
next analysis can be started.
The source was briefly tested with CO2 samples, using a He carrier of ca. 1 sccm to transport the
CO2 gas from ground potential into the source (Fig. 1). Analyzed 12C currents of 5-10 uA were
achieved, which is ca. one order ofmagnitude less than currents from graphite samples. Further tests
in progress seek to optimize source output and to quantify the memory effects of the source in the
case of CO2 samples.
PROGRESS ON THE 14C AMS SPECTROMETER
Figure 4 shows a schematic diagramof the HVEE biomedical 14C AMS spectrometer. Negative ions
are extracted from the ion source and mass analyzed by a small 90° permanent magnet. At the exit
ofthe magnet, 12C ions are collected in a Faraday cup for normalization; ions with a mass of 14 pro-
ceed to pass a 90° electrostatic analyzer (ESA), the tandem accelerator with a 180° ESA in its ter-
minal and a magnetic deflector before they are collected in a particle detector. A detailed descrip-
tion, together with the principles of background reduction of the instrument, is given elsewhere
(Mous et aL 1997).
Since the early tests on the system, various improvements have been made to optimize the beam
optics. A remotely controlled power supply in the high-voltage terminal for the adjustment of the
D. J. W. Mous etal.
70
60
ESA and a gridded lens following the high-energy (HE) tube were incorporated.
5. Ion Sourcefor theHVEE Mass Spectrometer 287
INLET
180 ELECTROSTATIC
DEFLECTOR
GC OR CNN
HE ACCEL. TUBE
GRIDOED
LENS
1111111 n
-----------
Fig. 4. Schematic layout of the HVEE 14C AMS spectrometer
ANALYSIS
MAGNET IONIZATION
OR
SSB DETECTOR
To evaluate the ion optical quality ofthe accelerator, the 13C2+ current in the HE Faraday cuplocated
just in front of the detector was measured during a scan of the low energy (LE) steerer and the 180°
ESA in the terminal. Figure 5 presents the results. Both traces show a flat-top tuned transmission,
indicating that the beam is transported through the system without loss. Furthermore, the figure indi-
cates the usefulness of the LE aperture during tuning of the system.
T
Injector steerer voltage --* 1800 deflector voltage -*
Fig. 5. HE Faraday cup current as a function of injector steerer voltage and 180° electrostatic
analyzer voltage
6. 288 D. J. W. Mous et at.
CONCLUSION
The cooperation between HVEE and Oxford University has resulted in a unique, compact ion source
that accepts both graphite samples and CO2 samples from ground potential. The source will be
applied on the HVEE 14C AMS spectrometer dedicated to biomedical research. Early tests have
showed that analyzed 12C- currents of 50-100 ,uA are easily extracted from graphite samples,
whereas 5-101uA is obtained from CO2 samples. ,
Beam transmission of the HVEE 14C AMS spectrometer is flat-top tuned, which guarantees that
accurate 14C analysis can be achieved.
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