This document summarizes a study comparing a carbon nanotube membrane to a capillary tube for introducing gas samples to a mass spectrometer. Carbon nanotubes were grown within the pores of an aluminum oxide membrane using chemical vapor deposition. The selectivity and conductance properties of gases passing through the carbon nanotube membrane versus a capillary tube were then evaluated using the mass spectrometer. The study found the carbon nanotube membrane was more transmissive to methane than the capillary tube. Conductance through the two systems also differed in their dependence on total pressure for various gases.
This document provides an overview of various nanotechnology applications including DNA sequencing using nanopores, filtration, uses in clothing and sports, composites, nanomedicine, superconductors, magnetic nanowires, ferroelectrics, and dielectric nanostructures. It also discusses the business of nanotechnology and provides examples of research on growing superconducting lead nanowires, fabricating yttrium barium copper oxide superconductor nanowires, investigating the magnetic properties of ferromagnetic nanowires, and developing ferroelectric nanotubes and metamaterials using dielectric nanostructures.
Effect of Nanoporous Anodic Aluminum Oxide (AAO) Characteristics On Solar Abs...A Behzadmehr
Nanoporous anodic aluminum oxide (AAO) has been used in many different fields of science and technology, due to its great structural characteristics. Solar selective surface is an important application of this type porous material. This paper investigates the effect of nanoporous AAO properties, including; film thickness, pore area percentage and pore diameter, on absorption spectra in the range of solar radiation. The parameters were verified individually depending on anodization condition, and the absorption spectra were characterized using spectrophotometer analysis. The results showed that the absorptivity was increased with growth of the film thickness. Furthermore, increasing the pore diameter shifted the absorption spectra to the right range, and vice versa. The investigation revealed the presence of an optimum pore area percentage around 14% in which the absorptivity was at its maximum value.
Sebastiani - Nano-mechanical and microstructural characterization of MS-PVD N...thinfilmsworkshop
This document summarizes a presentation on nano-mechanical and microstructural characterization of niobium thin films deposited by magnetron sputtering. Key points discussed include:
- Four niobium coatings were produced by varying the applied bias voltage and substrate material.
- Nanoindentation testing revealed the coatings' hardness is not affected by the substrate at depths less than one tenth the coating thickness.
- Analysis of deformation mechanisms using FIB sectioning showed columnar grain sliding and recrystallization during plastic deformation.
- A thin surface oxide layer of around 10nm was found, which could impact the coatings' superconducting performance.
Rapid reduction of ultrathin films of graphene oxide on large area silicon su...Conference Papers
This document summarizes research on producing graphene oxide thin films on large silicon substrates using ultrasonic spray coating and rapid thermal reduction. GO droplets were spray coated in ethanol and overlapped to form uniform thin films. Films were reduced at 1100°C by rapid thermal processing (RTP), achieving sheet resistances of 1-4 kOhms/sq. Characterization with SEM, AFM, XPS and four-point probe showed the spray coating produced uniform, continuous thin films with increasing thickness for more spray passes. RTP effectively removed oxygen and produced conductive rGO with mostly sp2 bonding, while lower temperature reduction was less effective. Sheet resistance generally decreased with more spray passes due to increased thickness.
Nanoporous materials consist of an organic or inorganic framework with a regular porous structure, where pore sizes are generally 100 nm or smaller. They can be classified as bulk materials or membranes. Examples include activated carbon, zeolites, and cell membranes. Nanoporous materials have consistently sized pores that allow only certain substances to pass through while blocking others. They have a wide range of applications including catalysis, gas sensing, ion exchange, optics, and photovoltaics.
Carbon Nanotubes Effect for Polymer Materials on Break Down Voltage IJECEIAES
Epoxy resin composites reinforced to different types of carbon nano-particles have been fabricated. Carbon black (20, 30 and 40 wt. %), graphene (0.5 to 4 wt. %) and carbon nanotubes (CNT) (0.5 to 2 wt. %) were added with different weight percentages to epoxy. The dielectric strength of composites was tested in several conditions such as (dry, wet, low salinity and high salinity). The mechanical characterization showed that the nano-composite Polymer enhanced by using these particles in the tensile strength. Thermal gravimetric analysis shows effect of these nano-particles on the thermal structure of epoxy resin. Scanning Electron Microscopic test is used to characterize the dispersion of carbon nano-particles and to analysis the fractured parts in the nano scale.
This document provides an overview of various nanotechnology applications including DNA sequencing using nanopores, filtration, uses in clothing and sports, composites, nanomedicine, superconductors, magnetic nanowires, ferroelectrics, and dielectric nanostructures. It also discusses the business of nanotechnology and provides examples of research on growing superconducting lead nanowires, fabricating yttrium barium copper oxide superconductor nanowires, investigating the magnetic properties of ferromagnetic nanowires, and developing ferroelectric nanotubes and metamaterials using dielectric nanostructures.
Effect of Nanoporous Anodic Aluminum Oxide (AAO) Characteristics On Solar Abs...A Behzadmehr
Nanoporous anodic aluminum oxide (AAO) has been used in many different fields of science and technology, due to its great structural characteristics. Solar selective surface is an important application of this type porous material. This paper investigates the effect of nanoporous AAO properties, including; film thickness, pore area percentage and pore diameter, on absorption spectra in the range of solar radiation. The parameters were verified individually depending on anodization condition, and the absorption spectra were characterized using spectrophotometer analysis. The results showed that the absorptivity was increased with growth of the film thickness. Furthermore, increasing the pore diameter shifted the absorption spectra to the right range, and vice versa. The investigation revealed the presence of an optimum pore area percentage around 14% in which the absorptivity was at its maximum value.
Sebastiani - Nano-mechanical and microstructural characterization of MS-PVD N...thinfilmsworkshop
This document summarizes a presentation on nano-mechanical and microstructural characterization of niobium thin films deposited by magnetron sputtering. Key points discussed include:
- Four niobium coatings were produced by varying the applied bias voltage and substrate material.
- Nanoindentation testing revealed the coatings' hardness is not affected by the substrate at depths less than one tenth the coating thickness.
- Analysis of deformation mechanisms using FIB sectioning showed columnar grain sliding and recrystallization during plastic deformation.
- A thin surface oxide layer of around 10nm was found, which could impact the coatings' superconducting performance.
Rapid reduction of ultrathin films of graphene oxide on large area silicon su...Conference Papers
This document summarizes research on producing graphene oxide thin films on large silicon substrates using ultrasonic spray coating and rapid thermal reduction. GO droplets were spray coated in ethanol and overlapped to form uniform thin films. Films were reduced at 1100°C by rapid thermal processing (RTP), achieving sheet resistances of 1-4 kOhms/sq. Characterization with SEM, AFM, XPS and four-point probe showed the spray coating produced uniform, continuous thin films with increasing thickness for more spray passes. RTP effectively removed oxygen and produced conductive rGO with mostly sp2 bonding, while lower temperature reduction was less effective. Sheet resistance generally decreased with more spray passes due to increased thickness.
Nanoporous materials consist of an organic or inorganic framework with a regular porous structure, where pore sizes are generally 100 nm or smaller. They can be classified as bulk materials or membranes. Examples include activated carbon, zeolites, and cell membranes. Nanoporous materials have consistently sized pores that allow only certain substances to pass through while blocking others. They have a wide range of applications including catalysis, gas sensing, ion exchange, optics, and photovoltaics.
Carbon Nanotubes Effect for Polymer Materials on Break Down Voltage IJECEIAES
Epoxy resin composites reinforced to different types of carbon nano-particles have been fabricated. Carbon black (20, 30 and 40 wt. %), graphene (0.5 to 4 wt. %) and carbon nanotubes (CNT) (0.5 to 2 wt. %) were added with different weight percentages to epoxy. The dielectric strength of composites was tested in several conditions such as (dry, wet, low salinity and high salinity). The mechanical characterization showed that the nano-composite Polymer enhanced by using these particles in the tensile strength. Thermal gravimetric analysis shows effect of these nano-particles on the thermal structure of epoxy resin. Scanning Electron Microscopic test is used to characterize the dispersion of carbon nano-particles and to analysis the fractured parts in the nano scale.
An Attempt to Study MoO3-Like TCO Nanolayered Compound in Terms of structural...CrimsonPublishersRDMS
MoO3 thin films were prepared using a spray pyrolysis technique and characterized. XRD analysis showed the films crystallized in the orthorhombic α-MoO3 phase. AFM images showed the films consisted of parallelepiped shaped wires. The films exhibited good sensitivity (93%) and reproducibility to 500 ppm ethanol vapor at 300°C, suggesting potential for ethanol sensing applications.
SIMONA CAVALU_Surface Modification of Alumina/ Zirconia Ceramics Upon Differe...Simona Cavalu
The aim of this study was to prepare and to characterize the structure of Al2O3–3YSZ composites with 5% TiO2 addition
as well as the surface modification upon treatments with SnF2 and NaBF4, respectively. SEM micrographs showed the
controlled densification of the composites as an effect of 3YSZ and TiO2 addition to alumina matrix. By FTIR and XRD,
the characteristics of Al-O and Zr-O vibrations, respectively, the diffractions lines related to a-corundum and zirconia in
tetragonal phase were discussed. Qualitative and quantitative results obtained by XPS and ATR FTIR demonstrated that the
proposed materials are more sensitive to SnF2 than to NaBF4 treatment.
Ultrasonic atomization of graphene derivatives for heat spreader thin film de...Journal Papers
1) Researchers developed an ultrasonic atomizer system to deposit graphene oxide thin films on silicon wafers for applications in semiconductor manufacturing.
2) Graphene oxide was spray coated using the ultrasonic atomizer and then thermally reduced to improve its electrical and thermal conductivity.
3) Characterization of the reduced graphene oxide thin films found they have high coverage area above 90% with uniform thickness, low sheet resistance below 3 kΩ/sq, and thermal conductivity over 1000 W/mK making it suitable as a heat spreader material.
High voltage graphene nanowall trench mos barrier schottky diode characteriza...Journal Papers
The document describes a study investigating the use of graphene nanowalls (GNW) as an alternative barrier layer to titanium silicide in trench metal-oxide-semiconductor barrier Schottky (TMBS) diodes. GNW was grown on silicon trench structures using plasma enhanced chemical vapor deposition. TMBS diodes with GNW barriers were fabricated and their leakage currents measured at temperatures up to 423K, finding significantly lower leakage than diodes with titanium silicide barriers. Material and electrical characterization of the GNW-TMBS diodes showed potential for improved high-temperature performance over conventional metal barriers due to graphene's high thermal conductivity and heat dissipation properties.
Surface Morphological and Electrical Properties of Sputtered Tio2 Thin FilmsIOSR Journals
Titanium dioxide films were formed on quartz and crystalline p-Si (100) substrates by DC reactive magnetron sputtering method. Pure titanium target was sputtered at a constant oxygen partial pressure of 5x10-2 Pa, and at different sputtering powers in the range 80 – 200 W. The as-deposited films were annealed in air for 1 hour at 1023 K. The deposited films were characterized by studying the surface morphology by atomic force microscopy (AFM), electrical and dielectric properties from current-voltage and capacitance-voltage measurements. Atomic force micrographs of the films showed that the Rrms and Ra increased with the increase of sputter power from 80 to 200 W. The leakage current density was increased by increasing the sputtering power.
This document discusses mesoporous materials, including their classification, synthesis, and applications. Mesoporous materials have pore sizes between 2-50 nm and high surface areas between 400-1000 m2/g. They are commonly synthesized using a soft template method involving surfactants. Mesoporous materials have a wide range of applications including adsorption, chromatography, catalysis, sensors, and drug delivery due to their tunable pore sizes and large surface areas.
Detecting of NH3, CO2 polluted gases by using ZnO- In2O3 thin filmsijceronline
International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
Graphene field-effect transistor simulation with TCAD on top-gate dielectric ...TELKOMNIKA JOURNAL
1) The document presents a simulation of a graphene field-effect transistor (GFET) using technology computer-aided design (TCAD) software to analyze the influence of different top-gate dielectric materials.
2) The simulation examines silicon dioxide (SiO2), silicon nitride (Si3N4), aluminum oxide (Al2O3), and hafnium oxide (HfO2) as dielectric materials and investigates their effects on critical GFET parameters such as saturation drain current, on/off current ratio, and Dirac voltage.
3) The results show that using high-k dielectric materials like HfO2 leads to improvements in these parameters compared to SiO2, with
Structural and Morphological Properties of Mn-Doped Co3O4 ThinFilm Deposited ...IJERA Editor
In this study, a series of manganese (Mn)-doped Cobalt oxide (Co3O4)thin films were deposited on steel substrate by the sol-gel spin coat method and investigated the influence of doping concentrations of Mn in Cobalt ranging from 0.001% to 1% on physical, structural and morphological properties of Co3O4 thin films. Cobalt acetate[(CH3COO)2Co.4H2O], Mn acetate [C4H6MnO4.4H2O] and Isopropyl alcohol were used as starting material, dopant source and reagent respectively.X-ray diffraction analysis indicated that pureCo3O4 thin film iscrystallinein nature andcubic phase with [400] preferential orientation.For Mn doped films, three new peaks corresponding to the planes [310], [320] and [420] of orthorhombic MnO2 phase were observed.SEM micrographs showed that incorporation of Mn in Co site was found to influence the surface morphology of the films. All the films showed tetragonal shaped grains. TheEDAXanalysis revealedthe amount of Mn element in the sample increased with increasing dopant concentration.
Just basics of mesoporous materials!!The Break through came around 1992 by both Japanese and Mobil scientist on the soft template based synthesis of mesoporous materials
The document discusses the use of nanomaterials in plastics. It provides examples of common nanomaterials like carbon nanotubes, fullerenes, nanoclays, metal and metal oxide nanoparticles, and POSS nanostructures. These nanomaterials have precise structures at the 1-100 nanometer scale that can improve properties like strength, conductivity, and barrier performance when added to plastics. The document also notes that while nanotechnology is new term, nanomaterials themselves are not new and have existed for a long time in nature.
X-Ray Diffraction Analysis of the Microscopies of Some Corrosion-Protective B...IJMER
The document analyzes the microstructures of corrosion protective coatings produced from bitumens harvested in Nigeria using X-ray diffraction. The coatings were produced by bath dipping steel specimens in heated bitumen at 230°C. XRD analysis found the coatings contained different mineral phases constituting 3.75-4.847% of the coating. Coatings from the same bitumen source (KPB) varied in mineral composition, indicating microstructural variations. The KPB coatings exhibited the highest corrosion protection while coatings from Ondo S-A bitumen exhibited the lowest. The results provide information to improve bitumen composition and coating methods for better performance.
This document discusses topographic analysis and physical testing of dental materials. It describes various methods for analyzing surface topography, including contact methods using a profilometer and non-contact methods like confocal microscopy, SEM, and atomic force microscopy. Physical testing methods are also outlined, such as using a rheometer, colorimeter, XRD, DSC, and pycnometry to analyze properties like flow, color, structure, thermal transitions, and density. References are provided for additional information on techniques like SEM, atomic force microscopy, and confocal microscopy.
Nanostructures at metal oxide and semiconductor boundaries (Engl)Vladislav Shershulsky
This document summarizes Vladislav Shershulsky's background in researching electrochemical nanostructures through anodizing aluminum. It discusses how anodizing leads to self-organized pore formation through a non-equilibrium process. Shershulsky was part of a research group in the 1990s that proposed a model to explain pore size dependence on anodizing potential and performed early computer simulations of pore growth. The document outlines continued research prospects, including 3D simulations and models incorporating more physical effects. It concludes that surface nano-electrochemistry remains an active area confirming many of the original findings.
Chap XI : Outils de Simulation des modes opératoires (Plans d’expériences)Mohammed TAMALI
Les méthodologies utilisées par les humains, en rapport, avec les tentatives de compréhension des phénomènes physiques qui nous entourent, donnent un contrecoup général de la complexité de ces même systèmes que nous manipulons et prenons comme sujets dans nos études.
Le niveau de complexité des systèmes est élevé, à un niveau où toutes les tentatives ou essais de lancement de procédés expérimentaux laissent et obligent à considérer des erreurs. Encore plus, les effets tangents. Selon la théorie de l’évaluation des performances, l’exigence ‘comprendre’ le système n’a de réponse que si :
- Nous avons tellement d’informations que les recommandations des études ultérieures seront satisfaites,
- Nous avons des références, avec quoi on peut comparer,
- Nous avons un historique susceptible d’être retracé,
- Il y a une possibilité pour faire de l’expérimentation.
Les trois premiers cas satisfont à eux-mêmes. Si telle est la situation, ils nous clarifient l’image. Le quatrième critère exige que l’expérience se fasse effectivement pour que toutes les questions, relatives à un problème donné, soient élucidées. Le domaine de définition du modèle régissant le système étudié est plus ou moins profond que ses variables se meuvent d’une manière continue ou discrète dans les espaces position/temps.
Ces variables sont les facteurs du systèmes et peuvent évoluer selon des modalités changeantes.
The document provides information on the Boeing 737 NG fuel system. It describes the three fuel tanks, their capacities and fuel quantity indicators. It outlines the fuel pumps, valves and controls. It notes limitations on fuel temperature, imbalance and loading. Procedures for refueling, defueling and cross-feeding fuel between tanks are summarized.
An Attempt to Study MoO3-Like TCO Nanolayered Compound in Terms of structural...CrimsonPublishersRDMS
MoO3 thin films were prepared using a spray pyrolysis technique and characterized. XRD analysis showed the films crystallized in the orthorhombic α-MoO3 phase. AFM images showed the films consisted of parallelepiped shaped wires. The films exhibited good sensitivity (93%) and reproducibility to 500 ppm ethanol vapor at 300°C, suggesting potential for ethanol sensing applications.
SIMONA CAVALU_Surface Modification of Alumina/ Zirconia Ceramics Upon Differe...Simona Cavalu
The aim of this study was to prepare and to characterize the structure of Al2O3–3YSZ composites with 5% TiO2 addition
as well as the surface modification upon treatments with SnF2 and NaBF4, respectively. SEM micrographs showed the
controlled densification of the composites as an effect of 3YSZ and TiO2 addition to alumina matrix. By FTIR and XRD,
the characteristics of Al-O and Zr-O vibrations, respectively, the diffractions lines related to a-corundum and zirconia in
tetragonal phase were discussed. Qualitative and quantitative results obtained by XPS and ATR FTIR demonstrated that the
proposed materials are more sensitive to SnF2 than to NaBF4 treatment.
Ultrasonic atomization of graphene derivatives for heat spreader thin film de...Journal Papers
1) Researchers developed an ultrasonic atomizer system to deposit graphene oxide thin films on silicon wafers for applications in semiconductor manufacturing.
2) Graphene oxide was spray coated using the ultrasonic atomizer and then thermally reduced to improve its electrical and thermal conductivity.
3) Characterization of the reduced graphene oxide thin films found they have high coverage area above 90% with uniform thickness, low sheet resistance below 3 kΩ/sq, and thermal conductivity over 1000 W/mK making it suitable as a heat spreader material.
High voltage graphene nanowall trench mos barrier schottky diode characteriza...Journal Papers
The document describes a study investigating the use of graphene nanowalls (GNW) as an alternative barrier layer to titanium silicide in trench metal-oxide-semiconductor barrier Schottky (TMBS) diodes. GNW was grown on silicon trench structures using plasma enhanced chemical vapor deposition. TMBS diodes with GNW barriers were fabricated and their leakage currents measured at temperatures up to 423K, finding significantly lower leakage than diodes with titanium silicide barriers. Material and electrical characterization of the GNW-TMBS diodes showed potential for improved high-temperature performance over conventional metal barriers due to graphene's high thermal conductivity and heat dissipation properties.
Surface Morphological and Electrical Properties of Sputtered Tio2 Thin FilmsIOSR Journals
Titanium dioxide films were formed on quartz and crystalline p-Si (100) substrates by DC reactive magnetron sputtering method. Pure titanium target was sputtered at a constant oxygen partial pressure of 5x10-2 Pa, and at different sputtering powers in the range 80 – 200 W. The as-deposited films were annealed in air for 1 hour at 1023 K. The deposited films were characterized by studying the surface morphology by atomic force microscopy (AFM), electrical and dielectric properties from current-voltage and capacitance-voltage measurements. Atomic force micrographs of the films showed that the Rrms and Ra increased with the increase of sputter power from 80 to 200 W. The leakage current density was increased by increasing the sputtering power.
This document discusses mesoporous materials, including their classification, synthesis, and applications. Mesoporous materials have pore sizes between 2-50 nm and high surface areas between 400-1000 m2/g. They are commonly synthesized using a soft template method involving surfactants. Mesoporous materials have a wide range of applications including adsorption, chromatography, catalysis, sensors, and drug delivery due to their tunable pore sizes and large surface areas.
Detecting of NH3, CO2 polluted gases by using ZnO- In2O3 thin filmsijceronline
International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
Graphene field-effect transistor simulation with TCAD on top-gate dielectric ...TELKOMNIKA JOURNAL
1) The document presents a simulation of a graphene field-effect transistor (GFET) using technology computer-aided design (TCAD) software to analyze the influence of different top-gate dielectric materials.
2) The simulation examines silicon dioxide (SiO2), silicon nitride (Si3N4), aluminum oxide (Al2O3), and hafnium oxide (HfO2) as dielectric materials and investigates their effects on critical GFET parameters such as saturation drain current, on/off current ratio, and Dirac voltage.
3) The results show that using high-k dielectric materials like HfO2 leads to improvements in these parameters compared to SiO2, with
Structural and Morphological Properties of Mn-Doped Co3O4 ThinFilm Deposited ...IJERA Editor
In this study, a series of manganese (Mn)-doped Cobalt oxide (Co3O4)thin films were deposited on steel substrate by the sol-gel spin coat method and investigated the influence of doping concentrations of Mn in Cobalt ranging from 0.001% to 1% on physical, structural and morphological properties of Co3O4 thin films. Cobalt acetate[(CH3COO)2Co.4H2O], Mn acetate [C4H6MnO4.4H2O] and Isopropyl alcohol were used as starting material, dopant source and reagent respectively.X-ray diffraction analysis indicated that pureCo3O4 thin film iscrystallinein nature andcubic phase with [400] preferential orientation.For Mn doped films, three new peaks corresponding to the planes [310], [320] and [420] of orthorhombic MnO2 phase were observed.SEM micrographs showed that incorporation of Mn in Co site was found to influence the surface morphology of the films. All the films showed tetragonal shaped grains. TheEDAXanalysis revealedthe amount of Mn element in the sample increased with increasing dopant concentration.
Just basics of mesoporous materials!!The Break through came around 1992 by both Japanese and Mobil scientist on the soft template based synthesis of mesoporous materials
The document discusses the use of nanomaterials in plastics. It provides examples of common nanomaterials like carbon nanotubes, fullerenes, nanoclays, metal and metal oxide nanoparticles, and POSS nanostructures. These nanomaterials have precise structures at the 1-100 nanometer scale that can improve properties like strength, conductivity, and barrier performance when added to plastics. The document also notes that while nanotechnology is new term, nanomaterials themselves are not new and have existed for a long time in nature.
X-Ray Diffraction Analysis of the Microscopies of Some Corrosion-Protective B...IJMER
The document analyzes the microstructures of corrosion protective coatings produced from bitumens harvested in Nigeria using X-ray diffraction. The coatings were produced by bath dipping steel specimens in heated bitumen at 230°C. XRD analysis found the coatings contained different mineral phases constituting 3.75-4.847% of the coating. Coatings from the same bitumen source (KPB) varied in mineral composition, indicating microstructural variations. The KPB coatings exhibited the highest corrosion protection while coatings from Ondo S-A bitumen exhibited the lowest. The results provide information to improve bitumen composition and coating methods for better performance.
This document discusses topographic analysis and physical testing of dental materials. It describes various methods for analyzing surface topography, including contact methods using a profilometer and non-contact methods like confocal microscopy, SEM, and atomic force microscopy. Physical testing methods are also outlined, such as using a rheometer, colorimeter, XRD, DSC, and pycnometry to analyze properties like flow, color, structure, thermal transitions, and density. References are provided for additional information on techniques like SEM, atomic force microscopy, and confocal microscopy.
Nanostructures at metal oxide and semiconductor boundaries (Engl)Vladislav Shershulsky
This document summarizes Vladislav Shershulsky's background in researching electrochemical nanostructures through anodizing aluminum. It discusses how anodizing leads to self-organized pore formation through a non-equilibrium process. Shershulsky was part of a research group in the 1990s that proposed a model to explain pore size dependence on anodizing potential and performed early computer simulations of pore growth. The document outlines continued research prospects, including 3D simulations and models incorporating more physical effects. It concludes that surface nano-electrochemistry remains an active area confirming many of the original findings.
Chap XI : Outils de Simulation des modes opératoires (Plans d’expériences)Mohammed TAMALI
Les méthodologies utilisées par les humains, en rapport, avec les tentatives de compréhension des phénomènes physiques qui nous entourent, donnent un contrecoup général de la complexité de ces même systèmes que nous manipulons et prenons comme sujets dans nos études.
Le niveau de complexité des systèmes est élevé, à un niveau où toutes les tentatives ou essais de lancement de procédés expérimentaux laissent et obligent à considérer des erreurs. Encore plus, les effets tangents. Selon la théorie de l’évaluation des performances, l’exigence ‘comprendre’ le système n’a de réponse que si :
- Nous avons tellement d’informations que les recommandations des études ultérieures seront satisfaites,
- Nous avons des références, avec quoi on peut comparer,
- Nous avons un historique susceptible d’être retracé,
- Il y a une possibilité pour faire de l’expérimentation.
Les trois premiers cas satisfont à eux-mêmes. Si telle est la situation, ils nous clarifient l’image. Le quatrième critère exige que l’expérience se fasse effectivement pour que toutes les questions, relatives à un problème donné, soient élucidées. Le domaine de définition du modèle régissant le système étudié est plus ou moins profond que ses variables se meuvent d’une manière continue ou discrète dans les espaces position/temps.
Ces variables sont les facteurs du systèmes et peuvent évoluer selon des modalités changeantes.
The document provides information on the Boeing 737 NG fuel system. It describes the three fuel tanks, their capacities and fuel quantity indicators. It outlines the fuel pumps, valves and controls. It notes limitations on fuel temperature, imbalance and loading. Procedures for refueling, defueling and cross-feeding fuel between tanks are summarized.
Le mot du président - Georges-Antoine Strauch Groupe ARTICQUE
Georges-Antoine Strauch président du Groupe ARTICQUE, présente les sociétés et les missions du groupe au travers de sa présentation.
Ce diaporama a été réalisé et présenté en introduction lors des Rencontres annuelles Articque 2014, qui se sont déroulées le 29 janvier à Paris et organisées par le Groupe ARTICQUE.
Pour en savoir plus : http://www.articque.com/societe/rencontres-annuelles-2014/
This document provides an overview of thin film deposition methods and thin film characterization techniques. It discusses the objectives of the course, which are to provide an understanding of thin film deposition methods, their capabilities and limitations. Hands-on demonstrations and experiments will help participants understand each deposition method and stimulate discussion. The document then summarizes various thin film deposition techniques like evaporation, sputtering, chemical vapor deposition, their principles and examples of applications. It also summarizes various characterization techniques used to analyze thin films and determine properties like composition, structure, thickness and defects.
1. Hydrogen peroxide was discovered in 1818 and has the molecular formula H2O2.
2. It can be prepared in the laboratory by reacting dilute sulfuric acid with sodium peroxide or barium peroxide.
3. Commercially, it is manufactured by electrolyzing sulfuric acid or by reducing anthraquinone derivatives with hydrogen gas.
This study synthesized MIL-53(Al) crystals on anodized aluminum oxide discs and characterized their ability to adsorb CO2 gas. MIL-53(Al) crystals were successfully grown on the discs by reacting anodized aluminum oxide with 1,4-benzenedicarboxylic acid at 85°C. Characterization with SEM, nitrogen adsorption isotherms, and FTIR confirmed the synthesis of MIL-53(Al) crystals on the discs over time. Exposure of the crystals to CO2 gas resulted in approximately 300 mOD of adsorbed CO2 detected by FTIR spectroscopy. Future work will optimize reaction conditions and further study the CO2 adsorption dynamics and
Les Français prennent-ils leurs croyances pour la réalité ? Ipsos France
Les résultats 2015 de notre enquête annuelle Perils Of Perception (Réalité vs. Perceptions) met en évidence les préjugés des Français, mais aussi d’habitants de 32 autres pays, sur des problématiques sociétales, économiques et politique. L’un des principaux enseignements est que nous nous méprenons fortement sur de nombreux sujets !
This document provides an overview of electrochemistry and electrochemical cells. It defines key terms like oxidation, reduction, anode, and cathode. Oxidation occurs at the anode and involves losing electrons, while reduction occurs at the cathode and involves gaining electrons. Electrochemical cells convert chemical energy to electrical energy through redox reactions. A simple cell consists of two electrodes connected by a wire submerged in an electrolyte. Several examples of simple cells are described using zinc, iron or copper electrodes reacting with hydrogen ions in solution.
Corrosive poisons are chemicals that damage and destroy surfaces through erosion. Common corrosive poisons include sulfuric acid, nitric acid, hydrochloric acid, and carbolic acid. When ingested, these chemicals cause severe burning pain and inflammation of tissues in the mouth, throat, and stomach. Victims may experience shock, difficulty swallowing or speaking, and blackened or discolored tissues upon examination. Severe cases can result in coma or death. While some corrosive poisons like carbolic acid also act as narcotics, their primary danger is their corrosive properties which can cause permanent scarring when used in violent acid attacks known as vitriolage.
Quantum dots are semiconductor nanoparticles that confine electrons and holes in all three dimensions. They are made using different methods like lithography, colloidal synthesis, or epitaxy. Quantum dots have discrete energy levels that depend on their size and shape. They have potential applications in solar cells, LEDs, bioimaging, drug delivery, and anti-counterfeiting due to their tunable light emission properties.
Inhibition of Sulphuric Acid Corrosion of Mild Steel by Surfactant and Its Ad...IOSR Journals
Abstract: The corrosion inhibition effect of surfactant, N,N-Dimethyl-N-(2-Phenoxyethyl)dodecan-1- aminiumbromide(DPDAB) on mild steel corrosion in 0.5M Sulphuric acid was investigated by weight loss, potentiodynamic polarization and Electrochemical impedance spectroscopic techniques. DPDAB is an excellent inhibitor and its inhibition efficiency increases with increase in concentration and maximum inhibition efficiency was observed above the critical micelle concentration (CMC). The polarization curves reveal that DPDAB acts as mixed type inhibitor with predominantly of anodic type. The corrosion inhibition efficiency of DPDAB increases with increase in concentration and decreases with increase in temperature from 298K to 308K and then increases and shows maxima at 318K and then decreases at 328K.. The adsorption of the inhibitor on the mild steel in 0.5M H2SO4 was found to obey Langmuir’s adsorption isotherm. Scanning electronic microscopy (SEM) confirmed the existence of an adsorbed protective film on the metal surface. The kinetic and thermodynamic parameters were calculated and discussed.
This document provides an introduction to RNA sequencing (RNA-Seq) applications using next-generation sequencing technologies. It discusses how RNA-Seq can be used to identify which genes are expressed, detect differential gene expression between samples, identify splicing isoforms, and detect genetic variants and structural variations. The document reviews Illumina sequencing by synthesis, the most common platform, outlining the work flow from sample acquisition, RNA extraction and library preparation to sequencing. It also discusses considerations for different sample types and extraction methods.
Online Incremental One-Shot Learning of Temporal Sequences (Portuguese)Rafael Pinto
O documento é uma dissertação de mestrado sobre aprendizado online incremental de sequências temporais. O trabalho propõe várias extensões do algoritmo IGMN (Incremental Gaussian Mixture Network) para capacidades temporais, como TDIGMN, ESIGMN, MIGMN e RecIGMN. Os algoritmos são testados em tarefas de previsão de séries temporais e comparados com redes neurais temporais, demonstrando capacidade de aprendizado online, incremental e one-shot de sequências temporais.
Template synthesis and characterization of well aligned nitrogen containing c...madlovescience
This document describes the synthesis and characterization of nitrogen-containing carbon nanotubes produced through the pyrolysis of polyvinyl pyrrolidone on an alumina membrane template. The nanotubes were analyzed using various techniques which showed they had a hollow, vertically aligned structure with a significant amount of nitrogen incorporated into the carbon framework, as evidenced by elemental analysis, Raman spectroscopy, IR spectroscopy, and XPS. The template synthesis method allowed production of well-aligned nitrogen-containing carbon nanotubes with controlled morphology and composition.
Template synthesis and characterization of well aligned nitrogen containing c...tshankar20134
This document describes the synthesis and characterization of nitrogen-containing carbon nanotubes produced through the pyrolysis of polyvinyl pyrrolidone on an alumina membrane template. The nanotubes were analyzed using various techniques which showed they had a hollow, vertically aligned structure with a significant amount of nitrogen incorporated into the carbon framework, as evidenced by elemental analysis, Raman spectroscopy, IR spectroscopy, and XPS. The template synthesis method allowed production of well-aligned nitrogen-containing carbon nanotubes with controlled morphology and composition.
Maiyalagan,Template synthesis and characterization of well aligned nitrogen c...kutty79
The synthesis of well-aligned nitrogen containing carbon nanotubes by pyrolysis of polyvinyl pyrrolidone (PVP) on alumina membrane
template is described. The nanotubes were characterized by elemental analysis, electron microscopic analyses, Raman, IR and X-ray photoelectron
(XPS) spectroscopic techniques. SEM, transmission electron microscopy (TEM) and AFM images reveal the hollow structures and
vertically aligned features of the nanotubes. Raman spectrum shows the characteristic bands at 1290 cm−1 (D-band) and 1590 cm−1 (G-band).
IR spectral bands indicated the characteristic C–N bonds in carbon nanotubes. This confirms the presence of nitrogen atoms in the carbon
framework. The XPS and elemental analyses further indicate significant amount of nitrogen in the nanotubes. IR, elemental and XPS analyses
clearly provide evidence for the presence of nitrogen in carbon nanotubes.
Nitrogen containing carbon nanotubes as supports fortshankar20134
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2) The platinum nanoparticles were uniformly distributed on the nitrogen-containing carbon nanotube surface with an average particle size of 3 nm.
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Nitrogen containing carbon nanotubes as supports for pt–alternate anodes for ...tshankar20134
1) Nitrogen-containing carbon nanotubes were synthesized and used to support platinum nanoparticles as an alternative anode catalyst for direct methanol fuel cells.
2) The platinum nanoparticles were uniformly distributed on the nitrogen-containing carbon nanotube surface with an average particle size of 3 nm.
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2) The platinum nanoparticles were uniformly distributed on the nitrogen-containing carbon nanotubes with an average particle size of 3 nm.
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Nitrogen containing carbon nanotubes as supports formadlovescience
1) Nitrogen-containing carbon nanotubes were synthesized and used to support platinum nanoparticles as an alternative anode catalyst for direct methanol fuel cells.
2) The platinum nanoparticles were uniformly distributed on the nitrogen-containing carbon nanotube surface with an average particle size of 3 nm.
3) Cyclic voltammetry studies showed that the platinum nanoparticles supported on nitrogen-containing carbon nanotubes had higher catalytic activity for methanol oxidation compared to a conventional platinum on carbon black catalyst.
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This document summarizes methods for functionalizing carbon nanotubes (CNTs) with metal nanoparticles and applications of the resulting materials. It discusses several electrochemical methods for depositing metal nanoparticles onto CNTs, such as electrodeposition of noble metals like Pt, Pd, and Au. Electrochemical deposition allows control over nanoparticle size and distribution and produces high purity nanoparticles. The document also discusses chemical deposition methods and how the functionalized CNT materials can be used in applications like catalysis and fuel cells.
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Carbon nano tubes for concrete better constructionsriram1052
The document summarizes a presentation on the compressive strength and microstructure of carbon nanotubes-fly ash cement composites. It discusses adding different amounts of carbon nanotubes (CNTs) to fly ash cement mixtures and testing the density, compressive strength, and microstructure of the resulting composites. Testing included SEM, XRD, TGA, DTA, and EDS analyses. The results showed that adding 0.5-1.0% CNTs increased the density and compressive strength of the fly ash cement composites compared to mixtures without CNTs. Microstructural analysis revealed the CNTs were uniformly dispersed in the cement matrix.
This document discusses carbon nanotube-based gas sensors. Carbon nanotubes have properties that make them well-suited for use in gas sensors, including their electrical and mechanical properties. There are two main types of carbon nanotubes: single-walled carbon nanotubes and multi-walled carbon nanotubes. Research has focused on enhancing the sensitivity and performance of carbon nanotube gas sensors by modifying the nanotubes through methods like functionalization or depositing thin metal films. Carbon nanotube-based sensors have shown potential for detecting various gases like nitrogen dioxide, ammonia, hydrogen, methane, hydrogen sulfide and sulfur dioxide.
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Similar to Direct coupling of a carbon nanotube membrane to a mass spectrometer - contrasting nanotube and capilary tube introduction systems (20)
2. L.D. Miranda et al. / Journal of Membrane Science 344 (2009) 26–31 27
2. Experimental methods
2.1. Anodic aluminum oxide membrane
An aluminum strip (0.5 mm thick, purity 99.999%) was
degreased in acetone and partly covered with electroplating tape.
Exposed aluminum was electropolished and anodized using the
two-step process of Masuda and Satoh [15]. The initial aluminum
anodization step was conducted at 40 V in 0.3 M oxalic acid at 10 ◦C.
After 17 h the oxide layer was removed using a mixture of phos-
phoric acid (6 wt%) and chromic acid (1.8 wt%) over a period of 1 h
at 60 ◦C. The aluminum anodization was then repeated for 10 h.
A protective polymer coat was applied to the oxide surface, and
the remaining aluminum was removed using a saturated mercuric
chloride solution. The aluminum oxide membrane was subse-
quently etched in 5% phosphoric acid (45 min at 30 ◦C). Mechanical
removal of the polymer coating produced a freestanding AAO mem-
brane. The AAO membrane was then heated in air between two
quartz plates (30 min at 900 ◦C) [16] causing a phase transition from
amorphous to gamma alumina [17].
2.2. Carbon nanotube synthesis
In the first stage of carbon nanotube synthesis, the AAO mem-
brane was placed in a quartz tube furnace, edge-up in a quartz
boat. The furnace-tube was purged with argon and the temper-
ature was raised to 750 ◦C. After thermal stabilization, the argon
flow was maintained at 10.5 mL/min and ethylene was added to
the gas stream at 0.35 mL/min. Carbon deposition was allowed for
16 h, after which the flow of ethylene was terminated and the fur-
nace was cooled to room temperature with a continuing flow of
argon.
2.3. Preparation of the CNT membrane
The chemical vapor deposition process generated carbon nan-
otubes within the pores of the AAO membrane and deposited a thin
carbon film on the surface of the membrane. The carbon film was
removed (ion milled, GATAN 691) from both sides of the membrane,
producing a smooth surface. The open pores of the CNT membrane
produced in this process are shown in Fig. 1.
A membrane module was then created using vacuum epoxy to
mount the membrane on a stainless steel frit (Fig. 2). To demon-
strate that the vacuum epoxy could eliminate leaks around the edge
of the membrane, an extensive carbon deposition process was used
Fig. 1. Scanning electron microscope (Hitachi S-4800 Field Emission) image of the
CNT membrane surface after ion milling. The dark areas in the image are open pores,
the light rim around the pore is the CNT and the remainder substrate is the aluminum
oxide film.
Fig. 2. Schematic of the CNT membrane module.
to seal the pores of an AAO membrane with a thick carbon film. Mass
spectrometry results showed insignificant gas introduction around
the blocked membrane, ensuring that ion currents obtained with
the CNT membrane would be attributable to diffusion through the
CNT pores (results not shown).
2.4. Mass spectrometry experiments
The selectivity of the CNT membrane was examined using two
Airgas certified gas mixtures: Gas Mixture A was composed of
0.50% methane (CH4), 1.50% argon (Ar), 0.20% carbon dioxide (CO2),
10.00% oxygen (O2) and 87.80% nitrogen (N2). Gas Mixture B was
composed of 1.01% CH4, 2.04% Ar, 2.03% CO2, 14.96% O2, and 79.96%
N2. Mass spectrometry experiments were conducted using the sys-
tem shown in Fig. 3. The two-position stage rotary valve (Valco
Instruments Co. Inc.) in the center of Fig. 3 had four connections
whereby the inlet of the MS (Inficon, Transpector 2.0 Gas Ana-
lyzer System) could be connected directly to the CNT membrane
module or the CT (Restek, Hydrogard FS, 0.1 mm ID) without break-
ing vacuum. A fourth valve connection provided coupling to a
diaphragm pump. This diaphragm pump was used to reduce the
pressure within the CNT membrane module and the CT when
these inlets were not in use. This precluded sudden increases in
MS vacuum chamber pressure when the valve was switched to
either inlet. Experiments were begun after a steady baseline sig-
nal was observed. Gases were analyzed by their mass-to-charge
(m/z) ratio. The m/z signals of CH4, N2, O2, Ar, and CO2 were ana-
lyzed at 15, 28, 32, 40, and 44, respectively, using a Faraday cup
detector. Gas mixtures were delivered to either the CNT membrane
or the CT through a series of Swagelok valves. For direct compar-
ison of the CNT membrane and the CT introduction systems, inlet
flow rates were matched. This created similar total pressures inside
the MS ionization region and, thereby, similar ionization condi-
tions. The gas exhaust of both the CNT membrane module and the
CT setup was connected to a single exhaust line where flow rate
and pressure could be observed and controlled. Experimental runs
were performed at a steady flow rate over a range of pressures.
Total pressure inside the ionization region was measured using the
pressure-reading software of the Transpector, and ranged between
3.3 × 10−3 and 6.7 × 10−3 Pa.
3. Results and discussion
3.1. CNT membrane
The two-step anodization process developed by Masuda and
Satoh [15] creates a uniform and monodisperse array of pores.
The AAO membrane produced in this work was 70 m thick and
had channels 50 nm in diameter. The ethylene gas pyrolyzed into
a graphitic structure on the alumina surface [9]. CNTs within the
3. 28 L.D. Miranda et al. / Journal of Membrane Science 344 (2009) 26–31
Fig. 3. Schematic drawing of the mass spectrometry experimental setup.
membrane had an average wall thickness of 5 nm, and outside
diameters and lengths identical to those of the AAO pores. Slow
flow rates of ethylene at concentrations less than 3.5%, and lengthy
periods of deposition at 750 ◦C, produced uniform growth of CNT
walls. In contrast, rapid carbon deposition thickens the surface film
of carbon and obstructs CNT wall growth.
The AAO membrane has remarkable strength properties [18],
and AAO membrane strength can be improved by controlling
pore-cell dimension and crystalline structure through calcination
[17,19]. In addition, support by a stainless steel frit in the membrane
module reduced stress on the membrane and increased membrane
tolerance to high pressure differentials between the sample and the
mass spectrometer vacuum.
3.2. Raman spectrum of the CNT membrane
Raman spectra of carbon allotropes revealed the characteris-
tic crystal structure of the nanotubes. The extent of sp2 and sp3
bonding on CNTs produces a unique Raman fingerprint [20]. Fig. 4a
shows a Raman spectrum for the synthesized CNTs. All spectra
showed first-order Raman bands at ∼1350 cm−1 (D band) and
∼1580 cm−1 (G band). The D band to G band intensity ratio (ID/IG)
is linearly related to the degree of CNT crystallinity [21]. The ID/IG
value of 0.80 shown in Fig. 4a indicates a low degree of crystallinity
compared to highly oriented pyrolytic graphite. Raman spectra
and transmission electron microscope (TEM, Hitachi 7100) imagery
(Fig. 4b) of our CNTs confirmed a turbostratic structure [22–24].
3.3. Mass spectrometry
Fig. 5 shows MS ion currents produced by methane (˚CH4
) using
(a) capillary tube introduction and (b) CNT membrane introduc-
tion. Each horizontal section in Fig. 5 was produced during steady
state flow at constant pressure. The different section heights in
Fig. 5 were produced by successive pressure increases in the sys-
tem. Observations of the ion currents (˚G) produced by each gas
(G) were obtained in triplicate.
Gases that passed through the inlet systems were constantly
evacuated by the pumps achieving a steady state condition and
thus constant pressure inside the vacuum chamber. ˚G is propor-
tional to the partial pressure (PG) of each gas in the MS vacuum
chamber via the relationship ˚G = S·PG, where S is the MS sen-
sitivity factor. Then ˚G is proportional to the quantity of a gas
that passes through the inlet plane in a known amount of time.
Therefore, throughput (QG) of the inlet system is proportional to
˚G times a proportionality factor k, QG = k·˚G. The properties of
each gas and each introduction system were examined by averag-
ing the measured values of ˚G. The conductance (CG) of each gas
was measured using the following equation: CG = QG/ P where P
is the total pressure gradient. CG was normalized by the mole frac-
tion ( ) of each gas via the relationship C = CG/ . The normalized
conductance (C ) was then plotted against the total pressure on the
inlet system (Fig. 6). The results in Fig. 6 show distinct differences
in the transmission characteristics of the two introduction systems
and distinct differences for different gases.
C values in the CNT introduction system uniformly decrease
with increasing total pressure. The extent of this decrease is
greatest for CH4 and becomes progressively smaller in the order
CH4> N2 > O2 > Ar > CO2. The influence of total pressure on trans-
mission of CO2 in the CNT system is quite small. In contrast, C
in the CT system generally has an inverse order. Pressure effects
are smallest for CH4 and, for the remaining gases, the pressure-
dependent slopes are progressively less negative (N2 to O2) and
then increasingly positive (Ar to CO2).
Fig. 4. Results from analysis of CNT membrane: (a) Raman spectrum of the CNT
membrane and (b) TEM image of a CNT.
4. L.D. Miranda et al. / Journal of Membrane Science 344 (2009) 26–31 29
Fig. 5. Ion currents produced by CH4 using (a) capillary tube and (b) CNT membrane
introduction systems.
Graph b of Fig. 6 shows that N2 from Gas Mixture B has a some-
what less negative slope than the corresponding N2 signal of Gas
Mixture A. This is due to the increased concentration of CO2 in the
gas mixture, thus contributing CO+ fragment ions to the m/z 28
ion current signal. Nonetheless, the CNT and CT conductance trend
for N2 is real as this gas has the highest concentration in both gas
mixtures.
Fig. 6 shows, for each component gas, that CNT membranes
have relatively simple flux characteristics. Increasing total pressure
decreases the conductance of each gas. This simple behavior is not
observed in the CT introduction system, in which gas conductance
both decreases (N2) and increases (O2, Ar and CO2) with increasing
pressure. In each plot the dependence of normalized conductance
on pressure is the same for Gas Mixtures A and B. However, in each
case, normalized conductances are slightly higher for Gas Mixture
A. This offset arises because the ion currents (˚G) used to calculate
normalized conductance for each gas were not background cor-
rected for contributions of residual gas in the vacuum housing. The
experiments for each gas mixture were performed on different days
and thus a slight difference in the partial pressure of each residual
gas led to the observed offsets.
In Fig. 7 CNT and CT gas transmission characteristics as a function
of pressure are compared in the following form: C (CNT)/C (CT).
Fig. 7 shows that, relative to the CT system, the CNT membrane
is selectively transmissive to CH4 over a range of conditions. In
the case of N2, the CNT and CT introduction systems are generally
comparable (C (CNT)/C (CT)∼1) over a range of pressures. For the
remaining gases, O2, Ar and CO2, the CNT membrane is less conduc-
tive than the CT system, and the magnitudes of the differences in
transmission become larger with increasing pressure. The results
shown in Fig. 7 are in general agreement with previous compar-
isons of CNT gas transmission properties obtained through analysis
of discrete samples [14].
The synthesized CNT membranes have a low degree of crys-
tallinity (Fig. 4b), a high surface area, and thereby a high propensity
for adsorption [25]. The adsorption of gases to the surfaces of
nanotube-channels causes a temperature-dependent [26,27] and
Fig. 6. Normalized conductance (C ) against total pressure for Gas Mixtures A and
B using capillary tube and CNT membrane introduction system.
5. 30 L.D. Miranda et al. / Journal of Membrane Science 344 (2009) 26–31
Fig. 7. CNT membrane and capillary tube conductance ratios over the total pressure.
Fig. 8. CNT normalized transport resistance of each component gas with increasing
pressure.
pressure-dependent interfacial resistance to flow. The pressure
dependence of the resistance (R) to transport caused by interac-
tion of gas with the CNT can be expressed in terms of gas flux (J)
and the P via the relationship RG = P/JG. Since gas flux (JG) is
directly proportional to the ion flux via the relationship JG = KG·˚G,
the proportionality factor, KG, is then eliminated by normalizing
the flux data to the flux at one atmosphere total pressure. As such,
RG(normalized) = P/˚G.
Fig. 8 shows RG for the CNT membrane normalized to RG at 1
atmosphere total pressure. The data shown in Fig. 8 were obtained
over a wider range of pressures than the studies which compared
CNT and CT transmission characteristics.
Fig. 8 shows that flux resistance in the CNT introduc-
tion system increases with increasing pressure in the order
N2 > CH4 > O2 > Ar > CO2. This effect is consistent with gas interac-
tions with CNT walls becoming increasingly important at higher
pressures. The pore geometry of our CNTs is characterized by a
Knudsen number greater than 1, where the flow regime is dom-
inated by particle–surface collisions rather than particle–particle
collisions. The adsorption of gas molecules into the CNT channel
walls at increased pressures has been shown by others [12–14,27]
to lead to a deviation from pure Knudsen behavior and is hypoth-
esized to be the cause of decreased conductance with increasing
pressure.
4. Conclusions
The template method was used to fabricate CNT membranes.
Carbon was deposited within the pores of an AAO membrane
using the chemical vapor deposition process. The properties of
a CNT/AAO membrane directly coupled to the inlet system of a
mass spectrometer were compared to those of a conventional MS
introduction system, a direct-feed capillary tube (CT). The CNT
membrane exhibited fast mass-transport properties and enhanced
transmission of CH4. In the case of N2, the transmission prop-
erties of the CNT and CT introduction systems were broadly
comparable. From the work of other groups [12–14,27], it is rea-
sonable to conclude that interfacial resistance – interactions of
gas molecules with CNT walls – caused the conductance of the
CNT membrane to decrease with increasing pressure, progressively
favoring the transmission of heavier molecules. However, since
gas conductance through the CT introduction increases with pres-
sure in the order CO2 > Ar > O2 > CH4 > N2, comparison of CNT vs.
CT gas transmission always showed the following order (CNT/CT):
CH4 > N2 > O2 > Ar > CO2.
This work demonstrates that CNT membranes can be viable
introduction systems for mass spectrometers. Since CNT mem-
branes can be internally [28] and externally [29] functionalized,
CNTs have considerable promise for providing membrane systems
with a wide range of transmission characteristics. Future work will
focus on functionalized CNT membranes and their selective trans-
mission properties for various analytes in solution.
5. List of symbols
ID Raman D band intensity
IG Raman G band intensity
G gas x
˚ ion current
P partial pressure
S sensitivity factor
Q throughput
k throughput proportionality factor
C conductance
C conductance (normalized)
P total pressure gradient
mole fraction
R transport resistance
J ion flux
K ion flux proportionality factors
Acknowledgments
• Supported by the NSF Florida–Georgia Louis Stokes Alliance for
Minority Participation (FGLSAMP) Bridge to the Doctorate sup-
plements awards HRD #0217675 and GEO #0503536.
• Supported by the Alfred P. Sloan Minority Ph.D. Fellowship pro-
gram.
• The Office of Naval Research provided financial support through
Grant No. N00014-03-1-0479 and Contract No. N00014-07-C-
720.
• The assistance of Dave Edwards (USF-COT) is gratefully acknowl-
edged for SEM analyses and Ashok Kumar and his students (USF)
are gratefully acknowledged for assistance with Raman Spec-
trometry.
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